[wasm][interp] Jiterp packedsimd shifts

[lewing]

Fill in some of the Jiterp tables with the PackedSimd intrinsics so that both aliased and direct PackedSimd calls in the interpreter also benefit from the Jiterpreter. Also reenable the aliased opcodes now that they will share the jiterpreter optimizations.

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[lewing]

Fixes the recent regressions in dotnet/perf-autofiling-issues#53419 without disabling the aliased opcodes (reverts #114659)

[Copilot]

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

src/mono/browser/runtime/jiterpreter-trace-generator.ts:3691

• Consider adding targeted tests to validate the early bitmask branch logic in emit_simd_2 to ensure that both the bitmask and fallback paths are exercised.

const bitmask = bitmaskTable[index];