feat!: implement collections using a BumpAllocator parameter

[bluurryy]

We reimplement the collections so instead of

struct BumpVec<'b, 'a, T, A, const MIN_ALIGN: usize, const UP: bool, const GUARANTEED_ALLOCATED: bool>
where
    MinimumAlignment<MIN_ALIGN>: SupportedMinimumAlignment,
    A: BaseAllocator<GUARANTEED_ALLOCATED>,
{ /* ... */ }

we now have

struct BumpVec<T, A: BumpAllocator> { /* ... */ }

This should clean up the api and implementation nicely but also add complexity in that we now have to account for A being anything and not just &BumpScope.

BumpAllocator will gain new methods for more optimized versions of allocate and friends so the generated code does not degrade.

With the new trait BumpAllocatorScope<'a> we can dish out objects for the 'a lifetime from functions like into_slice. Most functions don't need to know about the bump scope lifetime so BumpAllocator suffices. Some valid BumpAllocators can't implement BumpAllocatorScope<'a> like Bump (but &'a Bump can).

With this trait based design we should be able to replace Mut* collections by implementing the mut optimizations on their non-mut container equivalents whenever the BumpAllocator supports this.

We still need separate Mut* collections because in Mut* collections we need to protect the allocator and make sure no one can access it.

Todo:

• implement Bump{Vec,String} using BumpAllocator(Scope)
• implement MutBump{Vec,String} using BumpAllocator(Scope)
• replace (GuaranteedAllocated)Stats<'a, UP> with a new (GuaranteedAllocated)Stats<'a>
• add migration guide no, there are no straightforward migration steps from what i can tell
• rename to use Mut* prefix instead to match the collections (the collections themselves match the Fixed* prefix)
• review all docs and update where necessary