Basis Eval at arbitrary points

[jeremylt]

This PR adds the ability to interpolate the basis to arbitrary points:

• tests
• Chebyshev interpolating polynomials instead of Legendre
• map from Chebyshev coefficients to arbitrary points
• transpose direction
• create internal CeedBasis with "interpolation" from nodes to coefficients (combine interp + map to coeffs to one set of contractions)

[jedbrown]

Cool! It may be worth sketching out the implementation strategy in the documentation. It's something we'll be working on for GPU backends at some point so the math explanation won't be a waste. There will be choices about granularity. For example, the first tensor contraction could evaluate to the y-z planes of all the particles, or of a batch of particles, instead of just one particle at a time. I don't know if that's really a win.

Have you tested the pseudo-inverse approach with Q>P?

[jeremylt]

All backends pass now - ready to merge

[jedbrown]

woohoo