As a first step toward implementing SystemZ support for instr-ref-based
debug info tracking, this commit adds a basic implementation for the
previously absent `SystemZInstrInfo::isCopyInstrImpl`.

This is accomplished by adding a new flag called `isMoveReg` on the
relevant instructions and calling upon that bit of information to
implement the function. Which instructions to add the flag to was based
on the implementation of `SystemZInstrInfo::copyPhysReg`. The full list
of instructions is as follows:

#### General-Purpose Registers
- `lr`
- `lgr`
#### Floating Point Registers
- `ler`
- `ldr`
- `lxr`
#### Vector Registers
- `vlr`

The I5 operand of the instructions in RIE-f format is optional and
assumed 0 when not specified. This was not properly modeled thus far,
and is corrected with this PR. In addition, assembly and disassembly
tests are updated to reflect these changes

The current definition of the CKSM instruction uses GR64 for the first
operand. However, according to the Principles Of Operation the bits 0-31
of the first operand always remain unchanged. This PR changes the first
operand to GR32 to model this.
This has no further implication as this instruction is not used during
code generation.

This patch adds support for the next-generation arch15
CPU architecture to the SystemZ backend.

This includes:
- Basic support for the new processor and its features.
- Detection of arch15 as host processor.
- Assembler/disassembler support for new instructions.
- Exploitation of new instructions for code generation.
- New vector (signed|unsigned|bool) __int128 data types.
- New LLVM intrinsics for certain new instructions.
- Support for low-level builtins mapped to new LLVM intrinsics.
- New high-level intrinsics in vecintrin.h.
- Indicate support by defining  __VEC__ == 10305.

Note: No currently available Z system supports the arch15
architecture.  Once new systems become available, the
official system name will be added as supported -march name.

The "Size >= 32" check probably dates back to when TableGen integers
were 32-bit. Delete it and simplify code by using `isInt`/`isUInt`.

This pr includes fixes for original pr##116642.
Implementation for __builtin_setjmp and __builtin_longjmp for SystemZ..

This reverts commit 030bbc92a705758f1131fb29cab5be6d6a27dd1f.

Implementation for __builtin_setjmp and __builtin_longjmp for SystemZ.

To match the behavior of GNU binutils, output the nop family
of mnemonic aliases when disassembling.

The ATT assembler dialect on SystemZ seems to have been taken from the
existing ATT/Intel code. However, on SystemZ, ATT does not hold any
meaning. In reality, we are splitting the difference between GNU Asm
syntax and HLASM Asm syntax, so it makes sense to rename ATT to GNU
instead.

Co-authored-by: Tony Tao <tonytao@ca.ibm.com>