fix: unsound schema runtime check.

[Peefy]

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

• N
• Y

Closes #542

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

• kclvm/runtime/src/value/api.rs
• kclvm/runtime/src/value/val_type.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

fix: unsound schema runtime check including optional attributes and relaxed attributes

TODO: refactor runtime value union options.

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

• test/grammar/schema/optional_attr/fail**/**
• test/grammar/schema/relaxed/fail**/**

6. Release note

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

None

[coveralls]

Pull Request Test Coverage Report for Build 5368274088

• 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 87.988%

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Totals
Change from base Build 5368121804:	0.0%
Covered Lines:	2300
Relevant Lines:	2614

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 5368258770

• 4 of 17 (23.53%) changed or added relevant lines in 5 files are covered.
• 31 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-19.9%) to 68.09%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/runtime/src/stdlib/builtin.rs	0	2	0.0%
kclvm/runtime/src/value/val_plan.rs	0	2	0.0%
kclvm/runtime/src/value/api.rs	0	9	0.0%

Files with Coverage Reduction	New Missed Lines	%
compiler_base/session/src/lib.rs	31	50.0%

Totals
Change from base Build 5368121804:	-19.9%
Covered Lines:	30928
Relevant Lines:	45422

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💛 - Coveralls

[zong-zhe]

LGTM