feat: enhance plugin agent flag in APIs

[Peefy]

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

• N
• Y

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

• kclvm/api/src/service/service_impl.rs
• kclvm/api/src/service/util.rs

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

• 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

[coveralls]

Pull Request Test Coverage Report for Build 7953790579

Details

• -2 of 11 (81.82%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.001%) to 72.295%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/api/src/service/service_impl.rs	5	7	71.43%

Totals
Change from base Build 7948623196:	-0.001%
Covered Lines:	43899
Relevant Lines:	60722

---

💛 - Coveralls

[zong-zhe]

LGTM