Fix initlocals handling with mono interpreter

[BrzVlad]

Normally, we are too conservative, adding a MINT_INITLOCALS opcode even if all locals are initialized by IL code, which should be the common case anyway. However, we are not initializing locals coming from inlined methods.

We should be able to detect in the future when an uninitialized local is being used, and only then add the initlocals, both in the inlined method and normal case.

Failed tests: JIT/Directed/zeroinit/**

Tagging subscribers to this area: @BrzVlad, @lewurm
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