Fix(ts): escape doc comment terminator in generated JSDoc

[Ky0toFu]

Summary

• Escapes the */ terminator in TypeScript doc comments before emitting them into /** ... */ JSDoc blocks.
• Prevents schema doc_comment lines from closing the JSDoc block and injecting top‑level JavaScript into the generated module.

Root cause

• src/idl_gen_ts.cpp::GenDocComment previously wrote " *" + line + "\n" directly into a JSDoc block without escaping */.
• A crafted .fbs doc line such as */console.log('PWNED_TS_RCE_FROM_GENERATED_CODE')/* would:
  • close the JSDoc block (*/),
  • emit console.log(...) as top‑level JS that runs on import/bundling,
  • and reopen a block comment (/*) so the final */ from the generator still parses.

Fix

• For each doc comment line in GenDocComment, copy it into a local safe string and replace all occurrences of */ with *\/ before writing it into the JSDoc block.
• This keeps the emitted code as a standard /** ... */ JSDoc block (so IDE/tooling hover docs still work), but user‑controlled docs can no longer terminate the comment and inject code.

Notes

• The original issue also proposed rendering docs as line comments in TypeScript (// ...) to make early termination impossible by construction.
• Given that many IDEs and the TS language service rely on /** ... */ JSDoc for hover documentation and IntelliSense, this change implements the minimal, backwards‑compatible escape‑based fix first.

Fixes #8725.

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