Misc changes to reduce magic

• Certain structures (framebuffer/varying descriptors, probably others like shaders) get duplicated. A lot. This requires special care to avoid double allocations and to instead keep everything in sync. Handle this here.
• Misc dynamic structures
• Dynamic job descriptor allocation
• Bugfixes in watermark allocator, including forcing alignment
• Routine for uploading a memory structure immediately after the latest allocation, for the purpose of job payloads.
• Expand out the mystery field, previously named uniform count, to explicitly report uniform count, work registers, and then the remaining mystery fields (plural).
• Select between assembly and compilation from within panwrap, in this case to work around a missing feature in the Midgard assembler
• Ignore the IS_SEPERATE_SYMBOL checks since they are broken in practice, saving people from manually editing meson configuration (and instead raising a compile-error, rather than causing mysterious runtime issues, on incompatible configs).
• Don't print certain well-understood fields when they're zero