Update gVisor build to fresher version using new release tarball asset.

[Etienne Perot (EtiennePerot)]

This new release requires multiple files and is released as a tarball. gVisor asset handling code is updated to automatically handle this release format and extract it as necessary.

This build also contains the start of a series of upcoming startup/memory performance optimizations to make Substrate sandbox churn efficient.

Benchmarks between the previous gVisor build and this one:

CI benchmark suite:
                                                     │      old       │                    new                    │
                                                          │     sec/op     │     sec/op       vs base                  │
  ResumeActor/glutton_baseline_1_user/p50                   324.7m ±    3%    289.6m ±    2%  -10.79% (p=0.000 n=11)
  ResumeActor/glutton_baseline_1_user/p95                   373.4m ±    9%    328.6m ±    2%  -12.00% (p=0.000 n=11)
  ResumeActor/glutton_baseline_5_users/p50                  319.4m ±    1%    288.6m ±    1%   -9.65% (p=0.000 n=9)
  ResumeActor/glutton_baseline_5_users/p95                  367.6m ±    5%    341.7m ±   11%   -7.05% (p=0.024 n=9)
  ResumeActor/glutton_baseline_10_users/p50                 323.6m ±    1%    293.8m ±    2%   -9.22% (p=0.000 n=9+10)
  ResumeActor/glutton_baseline_10_users/p95                 396.2m ±    4%    372.1m ±    5%   -6.07% (p=0.001 n=9+10)
  ResumeActor/glutton_oversubscribe_15_users/p50            330.8m ±    2%    304.7m ±    1%   -7.89% (p=0.000 n=8+10)
  ResumeActor/glutton_oversubscribe_15_users/p95            402.7m ±    5%    390.4m ±    3%        ~ (p=0.083 n=8+10)
  ResumeActorColdStart/glutton_baseline_1_user/p50          227.0m ±   10%    211.6m ±   19%   -6.79% (p=0.003 n=11)
  ResumeActorColdStart/glutton_baseline_5_users/p50         231.5m ±    5%    216.3m ±    7%   -6.54% (p=0.004 n=9)
  ResumeActorColdStart/glutton_baseline_5_users/p95         246.4m ±    3%    230.2m ±    6%   -6.60% (p=0.000 n=9)
  ResumeActorColdStart/glutton_baseline_10_users/p50        217.4m ±   10%    193.5m ±    7%  -10.99% (p=0.001 n=9+10)
  ResumeActorColdStart/glutton_baseline_10_users/p95        241.8m ±    7%    231.2m ±    9%   -4.39% (p=0.022 n=9+10)
  ResumeActorColdStart/glutton_oversubscribe_15_users/p50   205.9m ±    6%    192.5m ±   28%        ~ (p=0.122 n=8+10)
  ResumeActorColdStart/glutton_oversubscribe_15_users/p95   247.1m ±    4%    229.6m ±  102%   -7.09% (p=0.043 n=8+10)
  SuspendActor/glutton_baseline_1_user/p50                  313.3m ±    7%    294.1m ±    4%   -6.14% (p=0.010 n=11)
  SuspendActor/glutton_baseline_5_users/p50                 304.6m ±    3%    289.1m ±    2%   -5.10% (p=0.000 n=9)
  SuspendActor/glutton_baseline_10_users/p50                309.7m ±    3%    296.9m ±    3%   -4.13% (p=0.000 n=9+10)
  SuspendActor/glutton_oversubscribe_15_users/p50           320.6m ±    3%    305.3m ±    2%   -4.75% (p=0.001 n=8+10)

Manual benchmarks (GKE on a single c3-standard-88 node):

- p50 sandbox lifecycle time (from issuing resume to checkpointed):
  ┌─────────┬──────────┬───────────┬────────┐
  │ workers │   old    │    new    │ delta  │
  ├─────────┼──────────┼───────────┼────────┤
  │ 1       │ 795 ms   │ 565 ms    │ −28.9% │
  ├─────────┼──────────┼───────────┼────────┤
  │ 2       │ 801 ms   │ 590 ms    │ −26.4% │
  ├─────────┼──────────┼───────────┼────────┤
  │ 8       │ 902 ms   │ 759 ms    │ −15.9% │
  ├─────────┼──────────┼───────────┼────────┤
  │ 64      │ 3.25 s   │ 3.14 s    │ −3.4%  │
  ├─────────┼──────────┼───────────┼────────┤
  │ 88      │ 4.47 s   │ 4.30 s    │ −3.8%  │
  └─────────┴──────────┴───────────┴────────┘

- Sandbox starts per second:
  ┌─────────┬────────────┬────────────┬────────┐
  │ workers │    old     │    new     │ delta  │
  ├─────────┼────────────┼────────────┼────────┤
  │ 1       │ 1.256 ± 1% │ 1.755 ± 2% │ +39.7% │
  ├─────────┼────────────┼────────────┼────────┤
  │ 2       │ 2.482 ± 1% │ 3.393 ± 1% │ +36.7% │
  ├─────────┼────────────┼────────────┼────────┤
  │ 8       │ 8.81 ± 2%  │ 10.50 ± 2% │ +19.2% │
  ├─────────┼────────────┼────────────┼────────┤
  │ 64      │ 19.85 ± 3% │ 20.45 ± 1% │ +3.0%  │
  ├─────────┼────────────┼────────────┼────────┤
  │ 88      │ 19.70 ± 1% │ 20.58 ± 2% │ +4.5%  │
  └─────────┴────────────┴────────────┴────────┘