fix: StringToAny to Boolean rejects TRUE/True/T/Y spellings, for issue #7842

[WLLTB]

Fixes #7842

What this PR does / why we need it?

TypeUtils.castToJavaBean("TRUE", Boolean.class) returns false. All String-to-Boolean conversions go through StringToAny, whose boolean branch only accepted lowercase "true", while ToBoolean (used for every other source type) accepts TRUE/True/T/Y/YES and friends — so the String source type could never reach the richer logic.

Summary of your change

• StringToAny: boolean branch now accepts "true"/"T"/"Y" case-insensitively (matching ToBoolean's single-letter set and fastjson1's castToBoolean spellings); unrecognized strings keep the existing lenient FALSE fallback instead of throwing, since this converter is shared by JSONObject/JSONArray/JSONPath/list conversion paths.
• Added regression test core/src/test/java/com/alibaba/fastjson2/issues_7800/Issue7842.java.

Note: "1" is deliberately left as false — JSONObjectTest.test_invoke pins that behavior, and ToBoolean doesn't accept "1" either. Happy to flip it if maintainers prefer fastjson1's castToBoolean semantics there.

Verified: core 7992 passed (standard + -Dfastjson2.creator=reflect), fastjson1-compatible 1355 passed, root validate clean.

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed. (No docs impact.)