Extproc new logging bits

[melginaldi]

ext_proc: Add processing_effect to ExtProcLoggingInfo

Commit Message: Add a bit to track mutations within ext_proc filter state ExtProcLoggingInfo.

Additional Description: This bit will track if a mutation occurred, if continue_and_replace was used or if an immediate response was sent. This addition will help with observability by gaining visibility into what ext_proc mutations occur.
Memory Implication: Since the defined enum has 4 values I chose use enum class: char to store the values as chars rather than ints. Therefore each enum variable will only be 1 byte of memory.

Risk Level: Low

Testing: Added multiple integration tests to ext_proc_integration_test.cc to validate this bit is set correctly in all 4 scenarios: no mutations, content modified, continue and replace and immediate response

Release Notes: Added new logging bit processing_effect to ExtProcLoggingInfo Filter State to track mutation events per GRPC call. Proccessing_event can be either None, ContentModified, ContinueAndReplace or ImmediateResponse. The default is None except processing mode FULL_DUPLEX_STREAMED whose defualt is Content Modified.

Docs Changes: N/A
Platform Specific Features: N/A

/assign @yanjunxiang-google

[yanjunxiang-google]

@melginaldi Thanks for working on this. One suggestion is to keep the PR as in draft mode while you are getting the CI passing.

[melginaldi]

@melginaldi Thanks for working on this. One suggestion is to keep the PR as in draft mode while you are getting the CI passing.

Ack. Thanks for the suggestion! I didn't know I could convert it back to draft. Will send for review once the CI passes