Migrate ExplainExec and AnalyzeExec protobuf serde

[Phoenix500526]

Which issue does this PR close?

• Closes Proto: migrate ExplainExec + AnalyzeExec #23511.

Rationale for this change

Physical plan protobuf serialization is being moved from the central
dispatch module into each ExecutionPlan implementation. Co-locating
this logic with the corresponding execution plan makes the serialization
code easier to maintain and incrementally reduces the central downcast
chain.

What changes are included in this PR?

• Implement plan-local protobuf serialization and deserialization for
  ExplainExec.
• Implement plan-local protobuf serialization and deserialization for
  AnalyzeExec.
• Remove both plans from the live central serialization dispatch.
• Retain the deprecated compatibility methods as delegates to the new
  implementations.
• Preserve the existing protobuf wire format.
• Strengthen roundtrip tests to cover all stored fields, including every
  StringifiedPlan variant, metric categories, and explain formats.

Each execution plan migration is kept in a separate commit.

Are these changes tested?

Yes. The following checks pass:

• cargo fmt --all
• cargo clippy --all-targets --all-features -- -D warnings
• Full extended workspace test suite
• cargo test -p datafusion-proto --test proto_integration

The proto integration suite passes all 209 tests after rebasing onto the
latest main.

Are there any user-facing changes?

No. This is an internal refactor and does not change the protobuf wire
format or user-facing behavior.

[github-actions]

Thank you for opening this pull request!

Reviewer note: cargo-semver-checks reported the current version number is not SemVer-compatible with the changes in this pull request (compared against the base branch).

Details

     Cloning apache/main
    Building datafusion-physical-plan v54.1.0 (current)
       Built [  41.461s] (current)
     Parsing datafusion-physical-plan v54.1.0 (current)
      Parsed [   0.148s] (current)
    Building datafusion-physical-plan v54.1.0 (baseline)
       Built [  37.143s] (baseline)
     Parsing datafusion-physical-plan v54.1.0 (baseline)
      Parsed [   0.154s] (baseline)
    Checking datafusion-physical-plan v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.975s] 223 checks: 223 pass, 30 skip
     Summary no semver update required
    Finished [  81.445s] datafusion-physical-plan
    Building datafusion-proto v54.1.0 (current)
       Built [  61.426s] (current)
     Parsing datafusion-proto v54.1.0 (current)
      Parsed [   0.020s] (current)
    Building datafusion-proto v54.1.0 (baseline)
       Built [  61.496s] (baseline)
     Parsing datafusion-proto v54.1.0 (baseline)
      Parsed [   0.021s] (baseline)
    Checking datafusion-proto v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.354s] 223 checks: 222 pass, 1 fail, 0 warn, 30 skip

--- failure trait_method_marked_deprecated: trait method #[deprecated] added ---

Description:
A trait method is now #[deprecated]. Downstream crates will get a compiler warning when using this method.
        ref: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.49.0/src/lints/trait_method_marked_deprecated.ron

Failed in:
  method try_into_explain_physical_plan in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:710
  method try_into_analyze_physical_plan in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:710
  method try_from_explain_exec in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:710
  method try_from_analyze_exec in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:710

     Summary semver requires new minor version: 0 major and 1 minor checks failed
    Finished [ 125.909s] datafusion-proto

[codecov-commenter]

Codecov Report

❌ Patch coverage is 73.91304% with 54 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.69%. Comparing base (16471ee) to head (a02a5a7).

Files with missing lines	Patch %	Lines
datafusion/proto/src/physical_plan/mod.rs	6.45%	29 Missing ⚠️
datafusion/physical-plan/src/analyze.rs	70.96%	11 Missing and 7 partials ⚠️
datafusion/physical-plan/src/explain.rs	93.85%	3 Missing and 4 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #23742    +/-   ##
========================================
  Coverage   80.69%   80.69%            
========================================
  Files        1090     1090            
  Lines      370357   370485   +128     
  Branches   370357   370485   +128     
========================================
+ Hits       298859   298963   +104     
- Misses      53684    53696    +12     
- Partials    17814    17826    +12     

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[adriangb]

Please resolve conflicts 🙏🏻

[Phoenix500526]

Please resolve conflicts 🙏🏻

Done