Rename `@maximum` and `@minimum` to `@max` and `@min`

Every single time I use one of these I want to type "max" or "min" until I remember "ah, right, I can't use well-established abbreviations here; I have to spell it all out, ugh".

The naming choices of @maximum and @minimum are weird and inconsistent for various reasons:

• "max" and "min" are very well established abbreviations for "maximum" and "minimum"; why do we have to spell it all out like that? It seems so extra.
• Abbreviations are used all throughout builtin function names. It's inconsistent and makes these two builtin functions stick out for no reason. If we don't want to use abbreviations, I guess we have to rename ptrCast to pointerCast. "Max" or "min" are as much, if not more so, well-understood abbreviation for "maximum" and "minimum" as "ptr" is for "pointer".
• Every developer expects these to be called "max" and "min". Most libraries/languages etc. use the abbreviations.
• They didn't do the same mistake in std.math: it's not std.math.maximumInt, it's std.math.maxInt and it's not std.math.maximum, it's std.math.max, and so on.
  So these builtin function names are inconsistent with std.math's equivalents (whatever the difference between these is supposed to be, anyway) as well. Especially if you change between the builtin functions and math.max or math.min, this weirdness in naming becomes especially noticeable and awkward.

[schmee]

Correct me if I'm wrong, but I believe builtins like this are designed to map directly to LLVM intrinsics, and in this case, the LLVM intrinsics are called "minimum" and "maximum" respectively: https://llvm.org/docs/LangRef.html#llvm-minimum-intrinsic. It would be strange to not follow the convention only for these two cases.

That does look like it might be the original reason why they were called that but now it seems kind of outdated to still design the Zig language around LLVM like that. Zig no longer depends on LLVM as its only backend and Zig should be backend-agnostic. LLVM shouldn't get any special treatment like that; it's just one of the backends.