config(ticdc): Add alias for "dispatcher" in dispatch rules

[zhaoxinyu]

What problem does this PR solve?

Issue Number: close #4423

What is changed and how it works?

Add alias for "dispatcher" in dispatch rules of sink configuration.
For example:

[sink]
dispatchers = [
    # these lines are completely equal
    {matcher = ['*.*'], dispatcher = "ts"},
    {matcher = ['*.*'], partition = "ts"},
 
    # these lines are completely equal
    {matcher = ['*.*'], dispatcher = "rowid", topic = "{schema}_{table}},
    {matcher = ['*.*'], partition = "rowid", topic = "{schema}_{table}},
]

Note: dispatcher and partition cannot be configured both. Thus, the following dispatch rule is invalid:

    {matcher = ['*.*'], dispatcher = "ts", partition = "rowid"},

Check List

Tests

• Unit test
• Integration test

Questions

Will it cause performance regression or break compatibility?

No

Do you need to update user documentation, design documentation or monitoring documentation?

Yes, the user doc should be updated.

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CharlesCheung96
• hi-rustin

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[codecov-commenter]

Codecov Report

Merging #5441 (084c033) into master (687e248) will decrease coverage by 0.3648%.
The diff coverage is 51.7857%.

Flag	Coverage Δ
cdc	60.6745% <51.7857%> (+0.0759%)	⬆️
dm	51.9340% <ø> (-0.5356%)	⬇️

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

@@               Coverage Diff                @@
##             master      #5441        +/-   ##
================================================
- Coverage   56.1240%   55.7591%   -0.3649%     
================================================
  Files           522        528         +6     
  Lines         65325      69646      +4321     
================================================
+ Hits          36663      38834      +2171     
- Misses        25094      27085      +1991     
- Partials       3568       3727       +159     

[ti-chi-bot]

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[Rustin170506]

rest LGTM

[Rustin170506]

@overvenus
Could you please take a look? Thanks! 💚 💙 💜 💛 ❤️

[Rustin170506]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 781913d

[zhaoxinyu]

/run-leak-test