Fix #22259 Allow complex float to complex double promotion

[aryandadwal2006]

Fixes #22259 and thereby allows complex float to complex double promotion without affecting anything else.

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Testing this PR locally

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[aryandadwal2006]

@elshorbagyx Hi , please take a look at my PR. I fixed the issue #22259 successfully.

[thewilsonator]

please add a test case for this.

[aryandadwal2006]

Added test case at: compiler/test/compilable/importc_complex_promotion.c

Test validates:
_Complex double x = 1 + 1.0if; // Main issue from #22259
_Complex double y = 2 + 3.0if; // Other mixed precision cases
_Complex double z = 1.0if + 2.0if; // Two float complex values
Existing float complex cases still work
Existing double complex cases still work

The test will fail before the fix and pass after.

[aryandadwal2006]

@thewilsonator Could you re-run the FreeBSD CI job?
The code compiled and tests ran, but there was an SSH teardown error.

[aryandadwal2006]

The FreeBSD CI job is failing on VM teardown (SSH infrastructure issue),
not on the actual code. The build and tests passed successfully before
the teardown. This is a known CI infrastructure issue on FreeBSD.

All other platforms should pass. Ready for review.

[thewilsonator]

All other platforms should pass.

They don't:

compilable/importc_complex_promotion.c(7): Error: cannot implicitly convert expression `_Complex(0.0F, 1.0F).opBinaryRight(1)` of type `_Complex!float` to `_Complex!double`
    _Complex double x = 1 + 1.0if;