refactor: use enum to dispatch SourceParser types

[neverchanje]

What's changed and what's your intention?

Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Merging #1896 (393c701) into main (5eb35c0) will decrease coverage by 0.00%.
The diff coverage is 10.71%.

@@            Coverage Diff             @@
##             main    #1896      +/-   ##
==========================================
- Coverage   70.70%   70.70%   -0.01%     
==========================================
  Files         610      610              
  Lines       79832    79835       +3     
==========================================
  Hits        56446    56446              
- Misses      23386    23389       +3     

Flag	Coverage Δ
rust	70.70% <10.71%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/source/src/connector_source.rs	0.00% <0.00%> (ø)
src/source/src/parser/mod.rs	0.00% <0.00%> (ø)
src/source/src/manager.rs	55.95% <50.00%> (+3.59%)	⬆️
src/source/src/high_level_kafka.rs	3.94% <100.00%> (ø)
src/connector/src/filesystem/file_common.rs	80.44% <0.00%> (-0.45%)	⬇️
src/common/src/types/ordered_float.rs	23.50% <0.00%> (-0.20%)	⬇️
.../src/executor/managed_state/aggregation/extreme.rs	90.26% <0.00%> (+0.26%)	⬆️

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[tabVersion]

LGTM