[WebAssembly] Fix issues combining coop threads and PIC (#208332)

This commit fixes a few issues that have surfaced in `wasm-ld`'s
handling of `--cooperative-threading` with `-shared`. Two primary issues
fixed are:

* The `__wasm_init_memory` function was not valid as it referenced
nonexistent locals. This was fixed by adjusting how locals are declared
to make this a bit more flexible.
* Combining data segments for PIC without extended-const is generalized
to only operate on active data segments and is now orthogonal to
threading. With coop threads there's a mixture of passive/active
segments (TLS is passive, other data is active) and the active segments
still need combining while TLS stays passive.

The latter fix ended up touching a few more areas. The first is that
`.tdata` sections are now sorted just before `.bss`, the end section,
rather than first. This is done to ensure that active segments when
combined can indeed start at a relative address of 0 (as required
without extended-const). This change resulted in a number of adjustments
for tests as the data is now sorted differently. Additionally
relocations in TLS segments needed adjusting since the previous
implementation implicitly only worked if `.tdata` is first.

GitOrigin-RevId: 662246dcb561a2645f238f67d74afbe739c75e32