Update lots of isa/*/*.clif tests to precise-output (#3677)

* Update lots of `isa/*/*.clif` tests to `precise-output`

This commit goes through the `aarch64` and `x64` subdirectories and
subjectively changes tests from `test compile` to add `precise-output`.
This then auto-updates all the test expectations so they can be
automatically instead of manually updated in the future. Not all tests
were migrated, largely subject to the whims of myself, mainly looking to
see if the test was looking for specific instructions or just checking
the whole assembly output.

* Filter out `;;` comments from test expctations

Looks like the cranelift parser picks up all comments, not just those
trailing the function, so use a convention where `;;` is used for
human-readable-comments in test cases and `;`-prefixed comments are the
test expectation.

cranelift/filetests/filetests/isa/aarch64/simd_load_zero.clif

@@ -1,4 +1,4 @@
-test compile
+test compile precise-output
 set unwind_info=false
 target aarch64
 
@@ -9,10 +9,16 @@ block0:
   return v1
 }
 
-; check:  movz x0, #1
-; nextln:  movk x0, #1, LSL #48
-; nextln:  fmov d0, x0
-; nextln:  ret
+; VCode_ShowWithRRU {{
+;   Entry block: 0
+; Block 0:
+;   (original IR block: block0)
+;   (instruction range: 0 .. 4)
+;   Inst 0:   movz x0, #1
+;   Inst 1:   movk x0, #1, LSL #48
+;   Inst 2:   fmov d0, x0
+;   Inst 3:   ret
+; }}
 
 function %f2() -> i32x4 {
 block0:
@@ -21,6 +27,13 @@ block0:
   return v1
 }
 
-; check:  movz x0, #42679
-; nextln:  fmov s0, w0
-; nextln:  ret
+; VCode_ShowWithRRU {{
+;   Entry block: 0
+; Block 0:
+;   (original IR block: block0)
+;   (instruction range: 0 .. 3)
+;   Inst 0:   movz x0, #42679
+;   Inst 1:   fmov s0, w0
+;   Inst 2:   ret
+; }}
+