feat: add Promisify type definition

[Alfred-Skyblue]

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

⚠️ Slowing down new functions

Warning: Slowing down new functions

As the VueUse audience continues to grow, we have been inundated with an overwhelming number of feature requests and pull requests. As a result, maintaining the project has become increasingly challenging and has stretched our capacity to its limits. As such, in the near future, we may need to slow down our acceptance of new features and prioritize the stability and quality of existing functions. Please note that new features for VueUse may not be accepted at this time. If you have any new ideas, we suggest that you first incorporate them into your own codebase, iterate on them to suit your needs, and assess their generalizability. If you strongly believe that your ideas are beneficial to the community, you may submit a pull request along with your use cases, and we would be happy to review and discuss them. Thank you for your understanding.

---

Description

fixed #3419

In PR #3419, when PromisifyFn received an async function, the return value was inferred as Promise<Promise<T>>, causing a type error. In this PR, we added the Promisify type to address this issue.

Additional context

---

🤖 Generated by Copilot at a4e30b9

Improved the type and value handling of async filters and functions in createFilterWrapper and FunctionWrapper. Added Awaited and Promisify types in ./types for compatibility with older TypeScript versions.

🤖 Generated by Copilot at a4e30b9

• Import and define Awaited and Promisify types in types.ts to handle values that may be promises (link)
• Use Promisify type in FunctionWrapper type in filters.ts to return the same type as the wrapped function (link)
• Use Awaited type in createFilterWrapper function in filters.ts to resolve or reject the promise with the same value as the wrapped function (link)
• Import Awaited and Promisify types from types.ts in filters.ts to use them in FunctionWrapper and createFilterWrapper (link)

[antfu]

A suppose Awaited is builtin in TypeScript isn't it?

[Alfred-Skyblue]

Awaited was introduced in TypeScript 4.5, here to consider compatibility.