Add percent clay input

[ltseng]

Record the percent clay of a soil (as a part of its texture), which, for soil scientists, is a method of identification.

"Again, some of the physical characteristics of the soil, the effervescence, the structure, the percent clay, those are all things that I use..." UT 1

This is a continuation of https://github.com/techmatters/terraso-product/issues/159, since we are not able to include % clay in the first release

Product Spec

• Soil texture/Rock fragments
• FAO Guidelines for Soil Description Percent clay guide page 38-39

Design

See Post-Capri Figma references below.

### Tasks
- [ ] https://github.com/techmatters/terraso-product/issues/992
- [ ] https://github.com/techmatters/terraso-product/issues/1007
- [ ] Implement percent clay

Acceptance criteria

• [ ] Add Percent Clay to project management data requirements list
• [ ] Percent Clay Info Sheet
• [ ] Add Percent clay to input option at depth level
• [ ] Percent Clay Data Input
• [ ] Add Percent clay to Soil Tab

[CourtneyLee333]

@DerekCaelin This user story doesn't seem to have the implementation task yet. I updated the description here to include the correct Figma references, and added the task list with the design review task.