Add documentation describing the problem and algorithm for coalescing
the LLVM functions generated from Carbon generic functions into fewer
LLVM functions, where the LLVM types permit it.
Update remaining parts of lowering, in particular the lowering of
aggregates, to handle lowering within a specific from a different file
than its generic. Look up information about a type in the current
specific and in its file rather than performing lookups for the type in
the generic and its file.
Remove or fix all remaining uses of raw `TypeId` in
lower/function_context and lower/handle*, so that the type from the
specific is consistently always used when lowering a specific function.
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Co-authored-by: Geoff Romer <gromer@google.com>
Geoff Romer
Alina Sbirlea
Richard SmithandGeoff Romer
