Cooperative rehashing in Map (puzpuzpuz#178)

Introduces cooperative rehashing for `xsync.Map` this means that goroutines that execute write operations, such as `Compute` or `Store`, may participate in table rehashing when the hash table grows or shrinks.

This behavior is always enabled, so the `WithSerialResize` function now acts as a no-op and is marked as deprecated.

Add documentation for parallel Map resize (puzpuzpuz#172)

Get rid of non-generic data structures and switch to maphash.Comparab…

…le as Map hash function (puzpuzpuz#163)

Changes:
* Version bump to v4.
* Minimal Golang version is now 1.24.
* All non-generic data structures are now removed. Generic versions should be used instead - they use the old names, but type aliases are present to simplify v3-to-v4 code migration.
* `MapOf`'s hasher API is gone. The default and only hash function is now based on `maphash.Comparable`.
* `Map`'s `Compute` API now supports no-op (cancel) compute operation.

Clarify docs for `LoadOrCompute` and `LoadOrTryCompute` (puzpuzpuz#154)

Add LoadOrTryCompute method to Map/MapOf (puzpuzpuz#153)

Add ToPlainMap/ToPlainMapOf utility functions (puzpuzpuz#151)

Improve RBMutex readme (puzpuzpuz#141)

Add NewMapOfWithHasher function (puzpuzpuz#137)

Improve readme (puzpuzpuz#136)

Introduce Map/MapOf configs and grow-only option (puzpuzpuz#132)