[refactor](load) Refactor the loader to expand the way data is written

[gnehil]

Proposed changes

Issue Number: close #xxx

Problem Summary:

In order to facilitate the expansion of more writing methods in the future, the writing part has been reconstructed. The main reconstruction contents are as follows:

1. Loader API
   The Loader API defines three behaviors:

   • load: write data to doris
   • commit: commit transaction
   • abort: abort transaction

2. TransactionHandler
   The TransactionHandler component is used to process all pre-committed transactions after the task or batch ends.
   When all tasks succeed, all pre-submitted tasks will be submitted; when some tasks fail, all pre-submitted tasks will be rolled back.
   The execution of transaction commit and rollback depends on the specific implementation of the commit and abort methods implemented by the loader.

Other changes:

1. update revision to 1.4.0-SNAPSHOT
2. add isSuccess method for RespContent to check whether the stream load is sucess internally

Checklist(Required)

1. Does it affect the original behavior: (Yes/No/I Don't know)
2. Has unit tests been added: (Yes/No/No Need)
3. Has document been added or modified: (Yes/No/No Need)
4. Does it need to update dependencies: (Yes/No)
5. Are there any changes that cannot be rolled back: (Yes/No)

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[JNSimba]

LGTM