feat: delete LogRecordDiffIgnoreField, add properties diffIgnoreNullValue

[qqxx6661]

delete LogRecordDiffIgnoreField, use LogRecordDiffField properties instead. add properties diffIgnoreNullValue
add unit test
add docs

[codecov-commenter]

Codecov Report

Merging #77 (8b2db0d) into master (4e02fef) will increase coverage by 1.01%.
The diff coverage is 100.00%.

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@@             Coverage Diff              @@
##             master      #77      +/-   ##
============================================
+ Coverage     61.92%   62.94%   +1.01%     
- Complexity      134      147      +13     
============================================
  Files            19       19              
  Lines           612      618       +6     
  Branches         88       91       +3     
============================================
+ Hits            379      389      +10     
+ Misses          188      186       -2     
+ Partials         45       43       -2     

Flag	Coverage Δ
unittests	62.94% <100.00%> (+1.01%)	⬆️

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Impacted Files	Coverage Δ
...l/logRecord/configuration/LogRecordProperties.java	25.00% <100.00%> (+4.41%)	⬆️
...l/logRecord/function/CustomFunctionObjectDiff.java	73.77% <100.00%> (+4.27%)	⬆️