[#5057] Added first part of CLI code

[justinmclean]

What changes were proposed in this pull request?

Added initial CLI to list information about metalakes, catalogs, schema and tables.

Why are the changes needed?

For a CLI.

Fix: #5057

Does this PR introduce any user-facing change?

No, but it add a new API.

How was this patch tested?

Unit test pass locally.

[justinmclean]

@shaofengshi @diqiu50 @yuqi1129 @mchades if you could review agian that would be appreciated

[shaofengshi]

Hi Justin, my comments are all resolved now, thank you!

I see you have replied Jerry's comments; I think he suggests to move the document to gravitino project's "docs" folder (not in cli module) and make its style consistent with others; besides, the error.sh and example.sh are sample commands, not for execution, which can be a part of documentation? You'd better double confirm with him.

[jerryshao]

Hi Justin, my comments are all resolved now, thank you!

I see you have replied Jerry's comments; I think he suggests to move the document to gravitino project's "docs" folder (not in cli module) and make its style consistent with others; besides, the error.sh and example.sh are sample commands, not for execution, which can be a part of documentation? You'd better double confirm with him.

Yes, docs should be in the "docs" folder, and it is user-facing doc, so any other content like test/contribute is not necessary to add.

Besides, these two shell scripts are just for demo purposes, it is not so useful and can be covered by doc, I suggest that you remove these two scripts here. You can add a script for running cli easily, like "gravitino.sh", for example "gcli.sh", this can be done in the later PR, but it should be in the "bin" folder.

[justinmclean]

All requested changes have been done, @jerryshao if you could please review, that would be appreciated.