Add Linear Interpolation as An Alternative to Geodesic Cross Sectional Interpolation

[walterjhudson]

What should we add?

Add Linear Interpolation as An Alternative to Geodesic Cross Sectional Interpolation
Estimate: 8
Priority: Should have
Story: As a researcher needing cross sectional data slices, I want to also perform interpolation with linear methods so that I can use datasets that are not georeferenced or am interested in the rhumb line.
Acceptance criteria:
Given implementation of liner interpolation methods
When performing cross section interpolation with the linear method
Then the results will be a two-dimensional path through the cross section.

[walterjhudson]

Steps to complete this issue:

1. [Time estimate: 1.5 hours] Perform Initial research and take notes on the ask ie decode the technical jargon.
2. [Time estimate: 2 hour] Find a sample dataset or fabricate a dataset that can be used with metpy.interpolate.cross_section
3. [Time estimate: 2 hour] With the sample dataset, run metpy.interpolate.cross_section and check the returned result.
4. [Time estimate 2 hour] Locate source code for function and understand default behaviour
5. [Time estimate 2 hour] Make code changes
6. [Time estimate 2 hour] Make unit tests that use geodesic and linear interpolation with dataset(s)
7. [Time estimate 0.5 hour] Update doc string for function
8. [Time estimate 1.5 hour] Optional can could spill over into next sprint session Create an example using the new feature