feat(go): run "go build" on generated code

[eladb]

To ensure the generated go code is formatted and compiles by executing go fmt
and go build on the output directory.

Similar to other languages, in order to be able to build the go module within mono-repos (and in the jsii repo itself), we need to be able to resolve local dependencies. This is done in the following way:

1. Create a list of dist/go candidates (based on the jsii.outdir relative to dependency package dirs)
2. Add to this list the current outDir, in case --outdir is used
3. Iterate over the module's dependencies (recursively) and for each candidate dist directory, check if we can find a <goModule>/go.mod file that contains a module <moduleName> directive.
4. If we find one, we append a replace directive with a relative path to our own go.mod which tells go fmt and go build to find the dependency locally.
5. At the end, we restore the original go.mod file so that the published one will not include the replace directives.

TESTING: this is primarily tested using the test:build target of jsii-pacmak which generates & builds the go code for the "calc" fixture (in all pacmak execution variants).

NOTE: running go fmt on the generated sources turned out to be problematic because sources are generated in parallel by default, and therefore it was not possible to resolve local dependencies at that time (which is required since go fmt processes go.mod).

Resolves #2463

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[MrArnoldPalmer]

Code looks good. Wondering if we should exclude 'go build' if the code-only option is set? Formatting would still be wanted so resolving dependencies is still necessary.

[eladb]

Code looks good. Wondering if we should exclude 'go build' if the code-only option is set? Formatting would still be wanted so resolving dependencies is still necessary.

Currently both fmt and build are executed only when we are actually building. I can look into resolving deps in the codegen case but I am currently leaning towards not formatting at all for now.

[mergify]

The title of this Pull Request does not conform with [Conventional Commits] guidelines. It will need to be adjusted before the PR can be merged.
[Conventional Commits]: https://www.conventionalcommits.org

[mergify]

The title of this Pull Request does not conform with [Conventional Commits] guidelines. It will need to be adjusted before the PR can be merged.
[Conventional Commits]: https://www.conventionalcommits.org

[aws-cdk-automation]

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