Add MET TC discrimiator selector to filter by distance to land

[mollybsmith-noaa]

Describe the New Feature

The MET TC app should have a selector allowing users to filter by distance to land.

Acceptance Testing

Automated MET TC tests must all pass.

Time Estimate

2 hours

New Feature Checklist

See the METplus Workflow for details.

• Complete the issue definition above, including the Time Estimate and Funding source.
• Fork this repository or create a branch of development.
  Branch name: feature_<Issue Number>_<Description>
• Complete the development and test your changes.
• Add/update log messages for easier debugging.
• Add/update unit tests.
• Add/update documentation.
• Push local changes to GitHub.
• Submit a pull request to merge into development.
  Pull request: feature <Issue Number> <Description>
• Define the pull request metadata, as permissions allow.
  Select: Reviewer(s), Project(s), Milestone, and Linked issues
• Iterate until the reviewer(s) accept and merge your changes.
• Delete your fork or branch.
• Close this issue.