RequiredTypeArgument variants of coerce from Data.Coerce

Usage of `coerce` quite frequently requires `TypeApplications` (or other mechanisms of specifying a type signature), which can get unwieldy quickly. I propose to add the following helpers to `Data.Coerce` to make this more ergonomic:

```haskell
{-# INLINE coerceFrom #-}
coerceFrom :: forall a -> forall b. Coercible a b => a -> b
coerceFrom _ = coerce

{-# INLINE coerceTo #-}
coerceTo :: forall a. forall b -> Coercible a b => a -> b
coerceTo _ = coerce

{-# INLINE coerceBetween #-}
coerceBetween :: forall a -> forall b -> Coercible a b => a -> b
coerceBetween _ _ = coerce
```

Start by reading README.md and PROPOSALS.md, then examine the proposed coerceFrom, coerceTo, and coerceBetween entry points in Data.Coerce. Done would require resolving the proposal and establishing whether these helpers should be added, along with the implementation and validation expected by the project.

Written by the indexing model from the issue text.