Standardize file naming and improve typings export

Renamed functions files to follow consistent camelCase convention. Added a missing type export for ITSInjex interface in the main index file, enabling better TypeScript type support and ensuring interfaces are available for external modules.

src/index.ts

@@ -1,8 +1,7 @@
 export * from './TSInjex';
-
 export * from './decorators/Inject';
 export * from './decorators/Register';
 export * from './decorators/RegisterInstance';
-
 export * from './functions/resolve';
 export * from './functions/register';
+export type * from './interfaces/ITSInjex';