Fix error handling and a percision issue in float core

[moste00]

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Detailed description

The following miscalenous fixes are added:

1- In librz/il/theory_fbasic, the exception-collecting code didn't handle RZ_FLOAT_E_INVALID_OP, a case block was added to handle it.

2- In librz/util/float/float.c, the code of rz_float_cast_sint was injecting the leading 1 into the conversion result of all FP formats, even though the binary80 format (used by e.g. x86) has an explicit leading 1, so it needs no injecting.

3- Also In librz/util/float/float.c, the code of rz_float_cast_sint was copying the bits from a source into a destination without caring about the relative lengths, it was changed to use the minimum length of the 2

Test plan

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Closing issues

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[wargio]

add a test