chrom : fix cargo clippy error in runtime

[NeverRaR]

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

• N
• Y

re #812

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

/kclvm/runtime

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

runtime code clean:
1. remove dead code
2. move rust code of system module to mod.rs in order to avoid use statements like base64:: base64
3. change the access permission of the unsafe function from pub to pub(crate)
4. fix other cargo clippy warnings

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 6719377355

• 35 of 1340 (2.61%) changed or added relevant lines in 20 files are covered.
• 471 unchanged lines in 8 files lost coverage.
• Overall coverage decreased (-17.8%) to 70.05%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/api/src/service/capi.rs	5	6	83.33%
kclvm/runtime/src/stdlib/assert_api.rs	0	1	0.0%
kclvm/runtime/src/value/val_fmt.rs	0	1	0.0%
kclvm/runtime/src/api/utils.rs	2	4	50.0%
kclvm/runtime/src/value/api.rs	0	2	0.0%
kclvm/src/lib.rs	0	2	0.0%
kclvm/runtime/src/manifests/mod.rs	1	5	20.0%
kclvm/runtime/src/value/val_schema.rs	2	6	33.33%
kclvm/runtime/src/collection/mod.rs	0	23	0.0%
kclvm/runtime/src/datetime/mod.rs	0	32	0.0%

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 6718648545:	-17.8%
Covered Lines:	38388
Relevant Lines:	54801

---

💛 - Coveralls