Enhancement(langserver): Add find references api

[my-vegetable-has-exploded]

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

• N
• Y
  re [Enhancement] Find reference #212

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

kusionstack/KCLVM/kclvm/tools/src/langserver

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

see more in issue212

• 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

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[Peefy]

@my-vegatable-has-exploded Pls sign the CLA and resolve the merge conflict.

[my-vegetable-has-exploded]

I have read the CLA Document and I hereby sign the CLA

[coveralls]

Pull Request Test Coverage Report for Build 3336910371

• 337 of 385 (87.53%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-29.9%) to 59.497%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/tools/src/langserver/go_to_def.rs	0	3	0.0%
kclvm/tools/src/langserver/mod.rs	81	93	87.1%
kclvm/tools/src/langserver/word_map.rs	73	85	85.88%
kclvm/tools/src/langserver/find_refs.rs	0	21	0.0%

Totals
Change from base Build 3334066564:	-29.9%
Covered Lines:	21022
Relevant Lines:	35333

---

💛 - Coveralls

[Peefy]

LGTM

[Peefy]

LGTM