Automatically upgrade flutter_rust_bridge Dart/Rust runtime versions when running generate

[fzyzcjy]

Changes

Close #1700

Checklist

• An issue to be fixed by this PR is listed above.
• New tests are added to ensure new features are working. Please refer to this page to see how to add a test.
• ./frb_internal precommit --mode slow (or fast) is run (it internal runs code generator, does auto formatting, etc).
• If this PR adds/changes features, documentations (in the ./website folder) are updated.
• CI is passing. Please refer to this page to see how to solve a failed CI.

Remark for PR creator

• ./frb_internal --help shows utilities for development.
• If fzyzcjy does not reply for a few days, maybe he just did not see it, so please ping him.

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (f7b8e9e) 99.26% compared to head (7947ee6) 99.26%.

Files	Patch %	Lines
frb_codegen/src/binary/commands.rs	0.00%	1 Missing ⚠️
...degen/src/library/codegen/polisher/auto_upgrade.rs	97.50%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1704   +/-   ##
=======================================
  Coverage   99.26%   99.26%           
=======================================
  Files         354      356    +2     
  Lines       14669    14749   +80     
=======================================
+ Hits        14561    14641   +80     
  Misses        108      108           

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