feat(cpp): Add bazel building and testing infrastructure

[slbotbm]

Which issue does this PR close?

Closes #2762

Rationale

What changed?

Adds bazel build system + stub classes and their tests + ci scripts

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

If AI tools were used, please answer:

1. Which tools? codex
2. Scope of usage? build system implementation
3. How did you verify the generated code works correctly? checking on local environment
4. Can you explain every line of the code if asked? Yes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.52%. Comparing base (2eefbc3) to head (9bed620).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2785      +/-   ##
============================================
- Coverage     67.53%   67.52%   -0.01%     
  Complexity      739      739              
============================================
  Files          1048     1048              
  Lines         84103    84103              
  Branches      60704    60716      +12     
============================================
- Hits          56795    56791       -4     
+ Misses        24950    24944       -6     
- Partials       2358     2368      +10     

Flag	Coverage Δ
csharp	67.06% <ø> (-0.19%)	⬇️
go	6.33% <ø> (ø)
java	54.83% <ø> (ø)
node	92.26% <ø> (-0.07%)	⬇️
python	0.00% <ø> (ø)
rust	69.71% <ø> (-0.01%)	⬇️

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see 13 files with indirect coverage changes

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[atharvalade]

Nice work on the infra setup. the CI integration and Bazel config are clean.

Two things to fix before merge though: the Expiry class in iggy.hpp has all its getters (expiry_type(), expiry_value(), value()) under private: unlike the other three classes, so it's completely opaque after construction (and the test can only SUCCEED() without asserting anything). Also, the genrule srcs hard-codes just src/lib.rs as soon as a second .rs file is added, Bazel won't detect changes to it and will serve stale cached builds. Swapping to glob(["src/**/*.rs"]) should fix that.

[slbotbm]

@atharvalade thanks for the review! those were some things that had been left over from when I was experimenting with the public interface. I've standardized all of the getter functions and corrected the bazel build file as well.

[slbotbm]

@hubcio Thanks for the review. I'll address the other two comments after thinking about the best approach