chore: prepare lambda layer catalog

[ava-silver]

What does this PR do?

Adds a generated Lambda layer catalog and derives the macro's existing runtime, architecture, tracer, and Extension layer lookups from it. Layer versions remain optional and require explicit configuration.

Motivation

Lambda layer metadata needs one generated source of truth before it can consume the shared Serverless catalog. This format-only preparation preserves the macro's current behavior.

Testing Guidelines

Not tested manually.

Additional Notes

This consumer intentionally retains Java 8, Node.js 12/14/16, and Python 2.7/3.6/3.7 even though the central catalog excludes them. Python 2.7/3.6/3.7 also retain their missing ARM layer names and current layer:undefined ARN behavior. An APM Serverless-approved behavior change must reconcile these runtimes before enabling the CloudFormation runtime campaign.

Types of changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog

[ava-silver]

• chore: reconcile lambda runtime support #270
• chore: prepare lambda layer catalog #269 👈 (View in Graphite)
• main

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.83%. Comparing base (ecc77d5) to head (2eac29c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #269      +/-   ##
==========================================
+ Coverage   86.27%   86.83%   +0.56%     
==========================================
  Files          18       19       +1     
  Lines        1690     1762      +72     
  Branches      345      352       +7     
==========================================
+ Hits         1458     1530      +72     
  Misses        231      231              
  Partials        1        1              

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