[lldb][AArch64] Add "memory tag read" command

This new command looks much like "memory read"
and mirrors its basic behaviour.

(lldb) memory tag read new_buf_ptr new_buf_ptr+32
Logical tag: 0x9
Allocation tags:
[0x900fffff7ffa000, 0x900fffff7ffa010): 0x9
[0x900fffff7ffa010, 0x900fffff7ffa020): 0x0

Important proprties:
* The end address is optional and defaults to reading
  1 tag if ommitted
* It is an error to try to read tags if the architecture
  or process doesn't support it, or if the range asked
  for is not tagged.
* It is an error to read an inverted range (end < begin)
  (logical tags are removed for this check so you can
  pass tagged addresses here)
* The range will be expanded to fit the tagging granule,
  so you can get more tags than simply (end-begin)/granule size.
  Whatever you get back will always cover the original range.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D97285