[CS0822] Allow function-local const-var for types which can be determined on compile-time

[vini-nu]

If function local constant variable type can be determined in compile-time, then it should be allowed.

Currently it erroring with "CS0822: Implicitly-typed variables cannot be constant" syntax error.

This looks better readability:

This looks worse readability:

    private void Demo(CancellationToken ct = default)
    {
        const var splitOptions =
            StringSplitOptions.TrimEntries |
            StringSplitOptions.RemoveEmptyEntries;
    }

[TahirAhmadov]

This has been requested previously (#106 - thanks HaloFour). I think the current opinion is that the work is not worth the benefit, given other priorities. Personally, I would like const splitOptions = StringSplitOptions.TrimEntries; - not even var.

[HaloFour]

See: #106