Add alternative element-local mapping (to be merged before #31)

[tristanmontoya]

This PR adds the element-local mapping from Guba et al. (2014), which first maps the quadrature node coordinates from the reference element using a bilinear mapping based on the four corner vertices, and then projects the mapped nodes onto a sphere of radius $a$ by scaling the resulting Cartesian coordinates $\boldsymbol{x}$ by $a/\lVert\boldsymbol{x} \rVert_2$. This is a quadrilateral version of what Michael Baldauf does for triangular grids (e.g. in this paper).

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.31%. Comparing base (dabbf64) to head (ca7118c).

Files with missing lines	Patch %	Lines
...olvers/dgsem_p4est/containers_2d_manifold_in_3d.jl	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #34 +/- ## ========================================== + Coverage 81.78% 82.31% +0.53% ========================================== Files 8 8 Lines 829 854 +25 ========================================== + Hits 678 703 +25 Misses 151 151 ```

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