Don't merge raw and quoted arguments when grouping functions

[mbrt]

The simplifier merges leaves using the same function under the same operator, e.g. or(from:a, from:b) becomes from:{a b}. When any of the merged leaves was raw (isEscaped: true, or a downloaded filter), the whole merged leaf was marked raw. Since quoting is skipped for all the arguments of a raw leaf, the non-raw ones silently lost their quotes:

or: [
  { from: 'John Smith' },
  { from: '-(foo bar)', isEscaped: true },
]

produced from:{John Smith -(foo bar)}, which matches mail from "John" or "Smith" instead of "John Smith".

Group raw and non-raw leaves separately instead, which now produces {from:"John Smith" from:-(foo bar)}. When the or is at the top of a rule it is split into one Gmail filter per leaf, as already happens for different functions (e.g. or(from:a, to:b)). Leaves that are all raw, or all non-raw, are grouped exactly as before.

A function can now produce two sibling leaves that differ only in the raw flag. They come out of a map, in random order, and the tree sort didn't tell them apart, so the order of the generated query (and with it the diff against Gmail) would change between runs. Sort non-raw leaves before raw ones to keep the output deterministic.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 41.86%. Comparing base (f51825d) to head (2a6434d).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #468      +/-   ##
==========================================
+ Coverage   41.37%   41.86%   +0.48%     
==========================================
  Files          54       54              
  Lines        3693     3698       +5     
==========================================
+ Hits         1528     1548      +20     
+ Misses       2063     2049      -14     
+ Partials      102      101       -1     

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