The symbol table data is stored in the linkedit segment,
but that segment may be in a different subcache from the
one containing the image headers. This occurs for the
arm dyld cache in macOS 13.

MachOFile::parse_dyld_cache_image already handled this
correctly, but readobj doesn't use that.

This is leftover from before subcaches were supported.

Delete fields that are duplicates of information in DyldCache and
DyldFile. This makes the enum similar to DyldSubCacheSlice.

Also extract common fields of the mapping enum.

Print the cache header and mappings for every subcache, instead
of only the primary cache file.

Also print the mapping slide information headers.

I think the offset can be useful in itself, and the address
and file offset are easily derived from it.

Change the methods on DyldCacheSlidePointer5 to simply extract
the bitfields, and leave other interpretation to the parser.

Also move PtrauthKey to DyldRelocationAuth, since it is not
an externally defined format.

This will be useful when supporting more slide versions.
Also shorten its name.

This takes the place of wrapping it in Option.
Also shorten its name.

Having a separate versioned DyldCacheRelocationPageIterator
is a flexibility that is not required, and combining them
is simpler.