gRPC Compile will now fail if a platform core has been modified.

[cmaglie]

Please check if the PR fulfills these requirements

See how to contribute

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• The PR follows
  our contributing guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• UPGRADING.md has been updated with a migration guide (for breaking changes)
• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

Before starting a compilation the platforms are checked for changes on the main files boards.txt, platform.txt, and programmers.txt. If a change is detected, the compile fails with an InstanceNeedsReinitializationError.
A gRPC client would need to perform a new Init call to update the in-memory structures, and retry the compile.

What is the current behavior?

If a core platform file (boards.txt, platform.txt, or programmers.txt) is modified, the compile is performed with the old files already loaded in memory, leading to #2523.

What is the new behavior?

The compile fails with an InstanceNeedsReinitializationError.

Does this PR introduce a breaking change, and is titled accordingly?

No

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.45%. Comparing base (870a48f) to head (185627b).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2551      +/-   ##
==========================================
+ Coverage   69.38%   69.45%   +0.06%     
==========================================
  Files         205      205              
  Lines       20162    20207      +45     
==========================================
+ Hits        13989    14034      +45     
  Misses       5050     5050              
  Partials     1123     1123              

Flag	Coverage Δ
unit	69.45% <100.00%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.