[MC][AsmParser] Parse event instructions

[asl]

• log.event in1, in2 aliased as event in1, in2
• log.event.first in1, in2 aliased as event.i in1, in2
• log.to_l1 in1, in2 aliased as event in1, in2
• log.to_l1 event.first in1, in2 aliased as event.i in1, in2

Spec:

• https://matter-labs.github.io/eravm-spec/spec.html#EventDefinition
• https://matter-labs.github.io/eravm-spec/spec.html#ToL1Definition

[atrosinenko]

I rechecked the spec, and aliased instructions seem to be indeed the same...

[atrosinenko]

Should work, but not all mnemonics are named as per the specification (see tests).

[atrosinenko]

Works, but see #441.

Tests (links to the HEAD of era-vm/asm-parser branch):

• events.s
• mnemonic-errors.s - rejecting invalid mnemonic suffixes