[ARM64] Only extend if src size is less than target

[yrp604]

Shink expr tree sizes with equivalent semantics. Developed on top of #7296 for my convenience.

This changes 3ish instructions:

• ldr variants -- conditionally emit the zero/sign extension when needed.
• fmov variants -- conditionally emit the zero extension when needed. I don't think there is existing test coverage for the ENC_FMOV_64VX_FLOAT2INT case, but the comment in decode_scratchpatd indicates it's only used with 64 bit registers.
• ubfx/ubfiz -- there are no encodings where the second argument is a different size than the first.

This removes about 700 total extensions from an arm64 ntdll.

Also added this check to the liftcheck wishlist in #2612

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[rssor]

There's a possibility that this winds up influencing types of temp registers due to spills in a way that is actually useful so I need to check on that a bit once I push some other stuff before accepting

[Copilot]

Pull Request Overview

This PR optimizes ARM64 intermediate language (IL) generation by eliminating unnecessary zero-extend and sign-extend operations when the source and target sizes are equal. The changes reduce the IL instruction count by approximately 700 extensions in ARM64 ntdll.

Key changes:

• Conditionally emit extensions in load instructions only when the load size is smaller than the target register size
• Remove unnecessary zero-extend operations from FMOV instructions when source and destination are the same size
• Remove redundant zero-extend wrappers from UBFX/UBFIZ bit-field operations

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[Copilot]

Inconsistent indentation: the continuation lines use spaces aligned to the opening parenthesis on line 3741, but the first parameter on line 3742 is indented too far to the right. Line 3742 should align with 'REGSZ_O(operand2)' on line 3741.

[Copilot]

Inconsistent indentation: the continuation lines starting at 3759 are indented too far to the right. They should align with the 'il.And' call on line 3758 for consistency with the project's formatting style.

Suggested change

	il.LogicalShiftRight(REGSZ_O(operand2),
	ILREG_O(operand2),
	il.Const(1, IMM_O(operand3))),
	il.Const(REGSZ_O(operand2), (1LL << IMM_O(operand4)) - 1))));
	il.LogicalShiftRight(REGSZ_O(operand2),
	ILREG_O(operand2),
	il.Const(1, IMM_O(operand3))),
	il.Const(REGSZ_O(operand2), (1LL << IMM_O(operand4)) - 1))));