[X86][APX] Use EVEX BLSI/BLSMSK for i8 patterns with EGPR (#226796)
This is a follow-up to #204746 and #205093, which added the i8 BLSI and
BLSMSK patterns.
The i8 BLSI/BLSMSK patterns were defined outside of Bls_Pats and always
selected the VEX forms, so with EGPR the register allocator could not
assign r16-r31 to their operands. Move them into Bls_Pats so that the
_EVEX variants are selected when EGPR is available.
Assisted-by: Claude Code
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Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>