Adds a new, cleaned up, HashMap implementation.
* Uses Robin Hood Hashing (https://en.wikipedia.org/wiki/Hash_table#Robin_Hood_hashing).
* Keeps elements in a double linked list for simpler, ordered, iteration.
* Allows keeping iterators for later use in removal (Unlike Map<>, it does not do much
for performance vs keeping the key, but helps replace old code).
* Uses a more modern C++ iterator API, deprecates the old one.
* Supports custom allocator (in case there is a wish to use a paged one).
This class aims to unify all the associative template usage and replace it by this one:
* Map<> (whereas key order does not matter, which is 99% of cases)
* HashMap<>
* OrderedHashMap<>
* OAHashMap<>
The freelook shortcuts now use the action system by proxy. This allows the actions system to be leveraged for input checking. When the shortcut changes, the respective action is updated.
This reverts commit a988fad9a0.
As discussed in #57725 and clarified in #57788, `SNAME` is not meant to be used
everywhere but only in critical code paths. For theme methods specifically, it
was by design that only getters use `SNAME` and not setters.
