This passes tests but it doesn't provide as big a window size as is
required to decompress larger streams.
The next commit in this branch will work towards that, without
introducing an additional buffer.
Use inline to vastly simplify the exposed API. This allows a
comptime-known endian parameter to be propogated, making extra functions
for a specific endianness completely unnecessary.
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
* add xz to std.compress
* prefer importing std.zig by file name, to reduce reliance on the
standard library being a special case.
* extract some types from inside generic functions. These types are the
same regardless of the generic parameters.
* expose some more types in the std.compress.xz namespace.
* rename xz.stream to xz.decompress
* rename check.Kind to Check
* use std.leb for LEB instead of a redundant implementation
