[interp] Constant folding for integers (mono/mono#17362)

[interp] Constant folding for integers (mono/mono#17362)

* [interp] Move instructions together

For easy check if an instruction is unary or binary operation. We consider conversion instructions to be unary operators and compare instructions to be binary operators.

* [interp] Add stloc.np also for longs

* [interp] Add stats for total number of emitted instructions

Also make the killed_instructions counter actually track the total amount of killed instructions. It was not previously tracking instructions killed as part of addition of stloc.np / movloc.

* [interp] Improve logging during cprop

Make dumping instruction support also InterpInst's not just compacted instructions.

* [interp] Constant folding of common unary operators

* [interp] Constant fold binary operations

* [interp] Remove MINT_CONV_U8_I4 opcode

It is equivalent with MINT_CONV_I8_U4.

Commit migrated from https://github.com/mono/mono/commit/ec653e70bfaba99e9fd88ceb3ff475eda83cb8f1