feat: anthropic initial instrumentation

[robertlaurin]

Just a small patch to fix context not propagating across fibers when anthropics client enumerates calls.

[fbogsany]

Do we need this puts in the test?

[robertlaurin]

Nope, will remove

[arielvalentin]

Did the instrumentation generator fail to add this to the test matrix? #1699

I added it and the tests are failing https://github.com/open-telemetry/opentelemetry-ruby-contrib/actions/runs/18062521999/job/51400805943?pr=1699

  	from /opt/hostedtoolcache/Ruby/3.1.7/x64/lib/ruby/gems/3.1.0/gems/opentelemetry-sdk-1.9.0/lib/opentelemetry/sdk.rb:63:in `configure'
  	from /home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/anthropic/test/test_helper.rb:20:in `<top (required)>'
  	from /home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/anthropic/test/opentelemetry/instrumentation/anthropic/instrumentation_test.rb:7:in `require'
  	from /home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/anthropic/test/opentelemetry/instrumentation/anthropic/instrumentation_test.rb:7:in `<top (required)>'
  	from /opt/hostedtoolcache/Ruby/3.1.7/x64/lib/ruby/gems/3.1.0/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:21:in `require'
  	from /opt/hostedtoolcache/Ruby/3.1.7/x64/lib/ruby/gems/3.1.0/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:21:in `block in <main>'
  	from /opt/hostedtoolcache/Ruby/3.1.7/x64/lib/ruby/gems/3.1.0/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:6:in `select'
  	from /opt/hostedtoolcache/Ruby/3.1.7/x64/lib/ruby/gems/3.1.0/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:6:in `<main>'
  /home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/anthropic/lib/opentelemetry/instrumentation/anthropic/instrumentation.rb:24:in `patch': uninitialized constant Anthropic::Internal (NameError)
  
            ::Anthropic::Internal::Transport::PooledNetRequester.prepend(Patches::PooledNetRequester)