Add asLeftF, asRightF, noneF, someF methods

[danicheg]

This adds asLeftF, asRightF, noneF, someF methods to AnySyntax, FEitherSyntax and FOptionSyntax.
Those methods are utterly useful in daily programming. They're replacing such constructs as:

none[Int].pure[F] // noneF
42.some.pure[F] // 42.someF
"foo".asLeft[Int].pure[F] // "foo".asLeftF

[benhutchison]

Not specifically related to this PR, but I note the general expansion of "lift operators" in mouse is not reflected in the old bare-bones example set in the README.

A new approach to documenting mouse is needed, I think, so that the library functions become more discoverable for "non-expert" users.