While fixing these I've also changed the way we store addresses into
ByteArray#. Addr# are composed of two parts: a JavaScript array and an
offset (32-bit number).

Suppose we want to store an Addr# in a ByteArray# foo at offset i.
Before this patch, we were storing both fields as a tuple in the "arr"
array field:

  foo.arr[i] = [addr_arr, addr_offset];

Now we only store the array part in the "arr" field and the offset
directly in the array:

  foo.dv.setInt32(i, addr_offset):
  foo.arr[i] = addr_arr;

It avoids wasting space for the tuple.

* For ByteArray-based bounds-checking, the JavaScript backend must use the
`len` field, instead of the inbuild JavaScript `length` field.

* Range-based operations must also check both the start and end of the range
for bounds

* All indicies are valid for ranges of size zero, since they are essentially no-ops

* For cases of ByteArray accesses (e.g. read as Int), the end index is
(i * sizeof(type) + sizeof(type) - 1), while the previous implementation
uses (i + sizeof(type) - 1). In the Int32 example, this is (i * 4 + 3)

* IndexByteArrayOp_Word8As* primitives use byte array indicies (unlike
the previous point), but now check both start and end indicies

* Byte array copies now check if the arrays are the same by identity and
then if the ranges overlap.

This patch includes all wasm32-specific testsuite fixes.

This patch adds the req_ghc_with_threaded_rts predicate to the
testsuite to assert the platform has threaded RTS, and mark some tests
as req_ghc_with_threaded_rts. Also makes ghc_with_threaded_rts a
config field instead of a global variable.

Previously we would cast pointers to uint64_t. However, implementations
are allowed to either zero- or sign-extend such casts. Instead cast to
uintptr_t to avoid this.

Fixes #23247.

Fixes #21054. Additionally, we can now check for range overlap
when generating Cmm for primops that use memcpy internally.

Commit 7566fd9de38c67360c090f828923d41587af519c with the fix for #22798 was
incomplete as it failed to handle MULTILINE_COMMENT pseudo-instructions, and
didn't completly fix the compiler panics when compiling with `-fregs-graph`.

Fixes #23002

req_cmm is more informative than js_skip