enhance: add limitation on find refs target number

[amyXia1994]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

close #893

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

enhance: add limitation on find refs target number
This PR simply limit find refs target to first 20 items. We could make it configurable in the future.

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

[Peefy]

LGTM

[coveralls]

Pull Request Test Coverage Report for Build 6969347917

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 87.82%

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Totals
Change from base Build 6967469271:	0.0%
Covered Lines:	2300
Relevant Lines:	2619

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 6969891755

Warning: This coverage report may be inaccurate.

We've detected an issue with your CI configuration that might affect the accuracy of this pull request's coverage report.
To ensure accuracy in future PRs, please see these guidelines.
A quick fix for this PR: rebase it; your next report should be accurate.

• 19 of 23 (82.61%) changed or added relevant lines in 2 files are covered.
• 471 unchanged lines in 8 files lost coverage.
• Overall coverage decreased (-15.7%) to 72.124%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/tools/src/LSP/src/find_refs.rs	3	7	42.86%

Files with Coverage Reduction	New Missed Lines	%
compiler_base/error/src/diagnostic/components.rs	6	0.0%
compiler_base/error/src/errors.rs	8	0.0%
compiler_base/session/src/lib.rs	26	58.06%
compiler_base/error/src/diagnostic/mod.rs	27	0.0%
compiler_base/error/src/diagnostic/style.rs	41	0.0%
compiler_base/error/src/diagnostic/diagnostic_message.rs	74	0.0%
compiler_base/error/src/emitter.rs	119	0.0%
compiler_base/error/src/diagnostic/diagnostic_handler.rs	170	0.0%

Totals
Change from base Build 6967469271:	-15.7%
Covered Lines:	41827
Relevant Lines:	57993

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💛 - Coveralls