feat(query): support ALTER <object> SET/UNSET TAG = value

[TCeason]

I hereby agree to the terms of the CLA available at: https://docs.databend.com/dev/policies/cla/

Summary

This PR implements the ALTER SET/UNSET TAG functionality, allowing users to manage tags on databases, tables, stages, and connections.

New Features:

• Support ALTER DATABASE/TABLE/STAGE/CONNECTION [IF EXISTS] SET TAG key = 'value', ...
• Support ALTER DATABASE/TABLE/STAGE/CONNECTION [IF EXISTS] UNSET TAG key, ...
• Automatically clean up tag references when dropping tagged objects (tables, stages, connections)
• Vacuum dropped tables also cleans up associated tag references

Restrictions:

• Tags cannot be set on built-in databases (default, system, information_schema, system_history)
• Tags cannot be set on tables in system databases (system, information_schema, system_history)
• Tags cannot be set on external catalog objects
• Tags cannot be set on temporary tables

Fix: #19220

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

---

This change is 

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: f459148994

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

[TCeason]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 60c5a0921e

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".