feat: add suggestions to no-empty-blocks

[k-yle]

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AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What is the purpose of this pull request?

Add sugggestions to no-empty-blocks. There are two different cases:

• @layer name {} becomes @layer name
• all other empty blocks like a {} become . This included unnamed layers such as @layer {}.

What changes did you make? (Give an overview)

Related Issues

Closes #476

Is there anything you'd like reviewers to focus on?

• We don't check if a block contains comments, because that would be convered by Rule Change: Allow no-empty-blocks to ignore comment-only blocks #477
• To the best of my knowledge, deleting all these different types of empty blocks is safe (except @layer as mentioned above). I have asked a senior colleague and Claude Opus 4.8, both of whom agreed.

[DMartens]

Thank you for the PR. Just found two small refactorings using more appropriate methods.
Also checked and tried ways to create a parse error / changing AST after removal but could not find one.
Would like the second reviewer to focus on this.