Cosmos: Fixup to Regex.IsMatch translation

[AndriySvyryd]

Fixup to #28121

• Throw a detailed exception for unsupported options when translating Regex.IsMatch (see discussion below)
• "Constantize" regex options via EvaluatableFilter (Cosmos: Add translator for Regex.IsMatch method #28121 (comment))
• Avoid generating empty options parameter if RegexOptions.None is specified (Cosmos: Add translator for Regex.IsMatch method #28121 (comment))

[roji]

Depend on #26410, right?

[smitpatel]

Not really blocked, the method translator should throw exception from itself.

[roji]

Don't we avoid doing that since it would block client eval?

[smitpatel]

Depends if we want to do client eval of certain things.

[roji]

OK, I'll bring this up in design, possibly with a proposal for #26410.

[smitpatel]

If you think we would need #26410 for this, we can wait till we put that one in plan.

[roji]

Just to figure out how we see things... If we're OK with throwing in method translators, #26410 becomes much less important, maybe even closeable (note it's already in the milestone).

I still think that ideally we just do #26410, e.g. by having translator return some NotTranslatableExpression (which wraps details); and then we don't have to discuss throwing because that always allows client eval and provides nicer exceptions. But we can discuss all that.