[GOBBLIN-1867] Refractor to add observability and makes extractor extendable [WIP]

[ZihanLi58]

Dear Gobblin maintainers,

Please accept this PR. I understand that it will not be reviewed until I have checked off all the steps below!

JIRA

• [ ] My PR addresses the following Gobblin JIRA issues and references them in the PR title. For example, "[GOBBLIN-XXX] My Gobblin PR"
  • https://issues.apache.org/jira/browse/GOBBLIN-1867

Description

• [ ] Here are some details about my PR, including screenshots (if applicable):

Refractor to make kafka extractor extendable.

Add logs for consumption rate to improve observability.

Change the consumption rate calculation strategy

Tests

• [ ] My PR adds the following unit tests OR does not need testing for this extremely good reason:

Commits

• [ ] My commits all reference JIRA issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

[codecov-commenter]

Codecov Report

Merging #3730 (de74c89) into master (2917b63) will increase coverage by 2.03%. The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #3730      +/-   ##
============================================
+ Coverage     47.43%   49.46%   +2.03%     
- Complexity     8691     9355     +664     
============================================
  Files          1731     1762      +31     
  Lines         66792    69138    +2346     
  Branches       7226     7877     +651     
============================================
+ Hits          31681    34200    +2519     
+ Misses        32351    31764     -587     
- Partials       2760     3174     +414     

see 797 files with indirect coverage changes

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