Add config file for the markdown checker

[breedx-splk]

This moves the configuration for the linkdown checker from commandline args over to a toml config file. This is intended to improve consistency between the java repos, and aligns with contrib #1986 and others.

Might need a refresh after open-telemetry/opentelemetry-java-instrumentation#14155 goes in.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.82%. Comparing base (360897b) to head (cff5820).

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7460   +/-   ##
=========================================
  Coverage     89.82%   89.82%           
  Complexity     6998     6998           
=========================================
  Files           798      798           
  Lines         21199    21199           
  Branches       2055     2055           
=========================================
  Hits          19041    19041           
  Misses         1496     1496           
  Partials        662      662           

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[breedx-splk]

I want this to align with open-telemetry/opentelemetry-android#1037 and open-telemetry/opentelemetry-java-contrib#1986 and open-telemetry/opentelemetry-java-instrumentation#14155 so making draft...

[jkwatson]

Thanks!