avoid calling coerce multiple times and only do it once

[Janther]

at the beginning of the parse.

Had to add an extra check in create-parser because the type grew in complexity.

[Janther]

Having second thoughts here as I'm not sure changing the compiler option's type and behaviour is worth the performance boost here.
Any thoughts @fvictorio ?
I'd have to further think about this one.

Update:
After some review I noticed that coerce is not needed at all since the compiler options will always be the Slang Language version, which is already a valid semver version and will not need a coercion.
I updated the PR accordingly.