* Make basepoint table constants static references
This ensures they have a fixed address and aren't duplicated across
compilation units.
Since they were already always borrowed, this changes the static values
to be `&'static` addresses to ensure they're always borrowed rather than
potentially copied.
* rustfmt
For the field element types `FieldElement` and `Scalar`, use inherent
constants instead of (non-const) functions to return these constant
values.
It's likely the original functions predate support for inherent
constants, but now that they're available, they're a better fit for
these sort of constant values.
