Enable static_assert checks in to_le_radix on to_be_radix also

[michaeljklein]

Problem

1. to_le_radix has static_assert's to ensure that the radix is a power of 2 in the range 2..=256, but to_be_radix lacks the equivalent checks
   a. (This includes tests for those checks)
2. to_le_radix's static_assert's are only enabled in constrained execution: see here

Happy Case

1. Use static_assert in to_be_radix to ensure that the radix is a power of 2 in the range 2..=256
2. Enable to_le_radix's static_assert's in unconstrained execution
3. Test these additional cases

Workaround

Yes

Workaround Description

Add the additional static_assert statements wherever to_le_radix/to_be_radix are used.

Additional Context

No response

Project Impact

Nice-to-have

Blocker Context

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response