mdatagen: get package name from metadata

[braydonk]

Description

I noticed a mistake in my previous PR #11232; some function calls did not pass the correct package name in (passing in "metadata" instead of the intended generated package name). This PR attempts to address the potential for this mistake to even occur by providing a wrapper generateFile function that automatically uses the generated package name from the metadata. The original version of the function that accepts a package name is intact for the templates that are going in the base package instead of the generated one.

Link to tracking issue

Bug originally from #11231
Fixes #11469

Testing

make mdatagen-test

Also added a custom generated package to the sample components, which would have caught the original bug.

Documentation

[braydonk]

I believe this change should not need a changelog. It is a fix for a bug that never made it into a release, and otherwise provides no user-visible changes.

[codecov]

Codecov Report

Attention: Patch coverage is 87.23748% with 79 lines in your changes missing coverage. Please review.

Project coverage is 91.48%. Comparing base (410b4f7) to head (19d7127).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...amplereceiver/internal/custom/generated_metrics.go	91.83%	27 Missing and 2 partials ⚠️
...plereceiver/internal/custom/generated_telemetry.go	63.79%	21 Missing ⚠️
...samplereceiver/internal/custom/generated_config.go	82.85%	8 Missing and 4 partials ⚠️
...ampleprocessor/internal/custom/generated_config.go	83.78%	4 Missing and 2 partials ⚠️
...pleprocessor/internal/custom/generated_resource.go	91.11%	4 Missing ⚠️
...mplereceiver/internal/custom/generated_resource.go	91.11%	4 Missing ⚠️
cmd/mdatagen/internal/command.go	66.66%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11468      +/-   ##
==========================================
- Coverage   91.58%   91.48%   -0.11%     
==========================================
  Files         440      446       +6     
  Lines       23754    24366     +612     
==========================================
+ Hits        21755    22291     +536     
- Misses       1627     1695      +68     
- Partials      372      380       +8     

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[braydonk]

The new coverage issue are just for the generated custom package I added, which I don't think are any more/less covered than the other generated metadata package and are just there as goldens anyway. So I think the codecov can be accepted.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[braydonk]

Unstale, looks like this fell through the cracks before the original feature got merged. I'll introduce a changelog since this now fixes a released feature.

[dmitryax]

Let's avoid the duplication. Maybe having a custom package in the processor and leaving the receiver as is.