fix: grant default CONNECT action for new created user

[yezizp2012]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

To fix #7596 , since we don't have concept of PUBLIC group yet, for newly create user, this PR will simply grant CONNECT action of the current database in session. Note that, like PostgreSQL we still need to grant other actions for new user, so that he can do more operation rather than just connect.

~ psql -h localhost -p 4566 -d dev -U root
psql (14.5 (Homebrew), server 9.5.0)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

dev=> create table a (v1 integer);
CREATE_TABLE
dev=> create user xxx with password 'abc';
CREATE_USER
dev=> \q
~ psql -h localhost -p 4566 -d dev -U xxx
Password for user xxx:
psql (14.5 (Homebrew), server 9.5.0)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

dev=> select * from a;
ERROR:  QueryError: Permission denied: Do not have the privilege
dev=> \q
~ psql -h localhost -p 4566 -d dev -U root
psql (14.5 (Homebrew), server 9.5.0)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

dev=> create materialized view mv1 as select * from a;
CREATE_MATERIALIZED_VIEW
dev=> grant all on materialized view mv1 to xxx;
GRANT_PRIVILEGE
dev=> insert into a values (1),(2),(3);
INSERT 0 3
dev=> \q
~ psql -h localhost -p 4566 -d dev -U xxx
Password for user xxx:
psql (14.5 (Homebrew), server 9.5.0)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

dev=> select * from mv1;
 v1
----
  3
  2
  1
(3 rows)

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features).
• I have demonstrated that backward compatibility is not broken by breaking changes and created issues to track deprecated features to be removed in the future. (Please refer the issue)
• All checks passed in ./risedev check (or alias, ./risedev c)

Documentation

If your pull request contains user-facing changes, please specify the types of the changes, and create a release note. Otherwise, please feel free to remove this section.

Types of user-facing changes

Please keep the types that apply to your changes, and remove those that do not apply.

• Installation and deployment
• Connector (sources & sinks)
• SQL commands, functions, and operators
• RisingWave cluster configuration changes
• Other (please specify in the release note below)

Release note

Please create a release note for your changes. In the release note, focus on the impact on users, and mention the environment or conditions where the impact may occur.

Refer to a related PR or issue link (optional)

Fix #7596

[codecov]

Codecov Report

Merging #7716 (d9eb72c) into main (4f54a70) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #7716   +/-   ##
=======================================
  Coverage   71.61%   71.62%           
=======================================
  Files        1098     1098           
  Lines      175036   175074   +38     
=======================================
+ Hits       125355   125396   +41     
+ Misses      49681    49678    -3     

Flag	Coverage Δ
rust	71.62% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
src/meta/src/manager/catalog/mod.rs	32.88% <ø> (+0.15%)	⬆️
src/meta/src/rpc/service/user_service.rs	0.00% <ø> (ø)
src/frontend/src/handler/create_user.rs	90.57% <100.00%> (+1.32%)	⬆️
src/frontend/src/handler/handle_privilege.rs	80.99% <100.00%> (+2.48%)	⬆️
...torage/src/hummock/local_version/pinned_version.rs	88.75% <0.00%> (-0.63%)	⬇️
src/meta/src/hummock/mock_hummock_meta_client.rs	65.78% <0.00%> (-0.53%)	⬇️
src/batch/src/task/task_execution.rs	52.88% <0.00%> (-0.51%)	⬇️
src/storage/src/hummock/compactor/mod.rs	80.95% <0.00%> (-0.20%)	⬇️
src/common/src/cache.rs	97.15% <0.00%> (-0.11%)	⬇️
... and 2 more

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[chenzl25]

LGTM