feat(async)!: remove deprecated APIs

[rami3l]

No description provided.

[peter-jerry-ye-code-review]

Function generic syntax has been updated from `fn name[T]` to `fn[T] name`

Category
Maintainability
Code Snippet
Before: pub fn Value::cast_from[T](value : T) -> Value
After: pub fn[T] Value::cast_from(value : T) -> Value
Recommendation
This appears to be a consistent change across the codebase. Ensure all similar functions are updated to use the new generic syntax fn[T] name.
Reasoning
The syntax change seems to be part of language evolution for better readability and consistency. Having generics before the function name makes the type parameters more prominent.

Async type signatures now use explicit `async` keyword

Category
Correctness
Code Snippet
Before: fn async_all[T](Array[() -> T!]) -> Array[T]!
After: async fn[T] async_all(Array[async () -> T!]) -> Array[T]!
Recommendation
Review all async function calls to ensure they properly use the new async keyword in function types
Reasoning
The explicit async keyword makes it clearer which functions are asynchronous and helps prevent misuse of async functions in synchronous contexts

Removal of deprecated async operations improves code clarity

Category
Maintainability
Code Snippet
Removed file: src/js/async_deprecated.mbt
Recommendation
Update any remaining code that might still use the old async APIs to use Promise directly
Reasoning
Removing deprecated code reduces maintenance burden and prevents usage of outdated patterns. The Promise-based API appears to be the new standard way to handle async operations.