**Description:**
This PR is to prepare removal of `string-cache`. Actually, this PR does not remove it. Instead, this PR only removes direct usages of `js_word!`s, especially in patterns.
**Related issue:**
- #4946.
**Description:**
## Bugfixes
- Exported `let`/`var` declarations in TypeScript namespaces should be mutable.
- Fix missing declaration of complex exported patterns in TypeScript namespaces.
- Preserve concrete TS namespaces.
## New Features
- Introducing [Verbatim Module Syntax](https://www.typescriptlang.org/tsconfig#verbatimModuleSyntax).
- Enum value will now be inlined whenever possible within a single module, optimizing runtime performance.
- Constant enums will be automatically eliminated when feasible, This can reduce bundle size.
- Added support for cross-referencing enum values.
## Deprecated
`TsEnumConfig` is deprecated
- The `treat_const_enum_as_enum` transform option is deprecated.
- The `ts_enum_is_readonly` assumption option is deprecated.
**BREAKING CHANGE:**
TypeScript Config is changed.
**Related issue:**
- Closes#5197
- Closes#5259
- Closes#7177
- Closes#7453
- Closes#7676
- Closes#7681
- Closes#7791
- Closes#7961
**Description:**
This PR also modifies React transform to use `FileName::Internal` and makes `SourceMapGenConfig` skips `FileName::Internal`.
**Related issue:**
- Closes#5272