feat: add clear method to cache object type

[shhonarmandi]

This commit updates the type definition of the Cache object to align with the native JavaScript Map data structure. This offers users access to clear method available on Map.

cache.clear(): Removes all key-value pairs from the cache (useful scenarios include user logout).

Relevant issue:
#2877

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[koba04]

Thank you for your PR!
As you mentioned, although the default Cache object is implemented with Map internally, it doesn't mean the Cache must be Map. We intentionally restrict the Cache interface to only APIs SWR uses internally so that users can implement their own Cache store without relying on Map.

Let me consider the clearing cache feature separately.

[shhonarmandi]

@koba04

Thank you for your feedback.

I updated the pull request and removed unnecessary methods and properties as you mentioned.