Add `operator<` to C++ class to allow lexicographic ordering of UUIDs.
This will be necessary when writing asset catalogs to disk in a predictable
(i.e. ordered) manner.
Put the `bUUID` class in the `blender` namespace, instead of the
`blender::bke` namespace.
As a result, some C++ code now correctly uses the C++ class, where
previously it would use the C struct and use implicit casting where
necessary. As a result, support for initializer lists had to be
explicitly coded and in another place an explicit `::bUUID` was
necessary to avoid ambiguity.
Rename the `UUID` struct to `bUUID`. This avoids a symbol clash on
Windows, which also defines `UUID`. This only pops up when a `UUID`
field is used in the DNA code, which is why it wasn't a problem before
(it will be once D12589 lands).
No functional changes.
Add `BLI_uuid` and `DNA_uuid_types.h` with a UUID implementation
following RFC4122 (https://datatracker.ietf.org/doc/html/rfc4122.html).
The following features are implemented:
- A struct of 128 bits that can be used in DNA definitions.
- Generation of version 4 UUIDs, that is, purely random ones.
- UUID equality function.
- String to UUID and UUID to string conversion functions that are
compatible with RFC4122.
- C++ stream operator that outputs the UUID as string.
This UUID will be used by the asset system, to uniquely identify asset
catalogs.
Reviewed By: Severin, jacqueslucke
Differential Revision: https://developer.blender.org/D12475
