arm: Split up MVE _Generic associations to prevent type clashes [PR107515]

arm: Split up MVE _Generic associations to prevent type clashes [PR107515]

With these previous patches:
https://gcc.gnu.org/pipermail/gcc-patches/2022-November/606586.html
https://gcc.gnu.org/pipermail/gcc-patches/2022-November/606587.html
we enabled the MVE overloaded _Generic associations to handle more
scalar types, however at PR 107515 we found a new regression that
wasn't detected in our testing:

With glibc's posix/types.h:
```
typedef signed int __int32_t;
...
typedef __int32_t int32_t;
```
We would get a `error: '_Generic' specifies two compatible types`
from `__ARM_mve_coerce3` because of `type: param`, when `type` is
`int` and `int32_t: param` both being the same under the hood.

The same did not happen with Newlib's header sys/_stdint.h:
```
typedef long int __int32_t;
...
typedef __int32_t int32_t ;
```
which worked fine, because it uses `long int`.

The same could feasibly happen in `__ARM_mve_coerce2` between
`__fp16` and `float16_t`.

The solution here is to break the _Generic down so that the similar
types don't appear at the same level, as is done in `__ARM_mve_typeid`

gcc/ChangeLog:
	PR target/96795
	PR target/107515
	* config/arm/arm_mve.h (__ARM_mve_coerce2): Split types.
	(__ARM_mve_coerce3): Likewise.

gcc/testsuite/ChangeLog:
	PR target/96795
	PR target/107515
	* gcc.target/arm/mve/intrinsics/mve_intrinsic_type_overloads-fp.c: New test.
	* gcc.target/arm/mve/intrinsics/mve_intrinsic_type_overloads-int.c: New test.