Update color scheme, branding, and streamline custom CSS

[kafitzgerald]

PR Summary

Updates the:

• color scheme - updates color scheme to use NSF NCAR colors for primary (with the exception of the dark theme primary color which is a lighter version of 1A658F to help with contrast), secondary, and table hover colors
• branding - color scheme updates and text in the footer (though this doesn't seem to be showing up any more either locally or in the deployed version Custom footer text no longer visible #132)
• streamlines custom CSS - merged all custom css into the style.css file and removed customizations either left over from prior themes, related to color schemes, or that didn't seem to be active (this could probably use a more thorough review)

Related Tickets & Documents

Closes #53
Closes #129

[github-actions]

Meowdy! See your PR preview:
🔍 Git commit SHA: 4288334
✅ Deployment Preview URL: https://NCAR.github.io/geocat-applications/_preview/133

[anissa111]

Huh, I definitely thought we needed theme_overrides.css separately, but as we're not using the same card things that necessitated its use in other repos and I bet my knowledge is outdated since the last time I played around with it, I'm good with removing it!

[kafitzgerald]

Huh, I definitely thought we needed theme_overrides.css separately, but as we're not using the same card things that necessitated its use in other repos and I bet my knowledge is outdated since the last time I played around with it, I'm good with removing it!

The docs were a little murky, but it seemed like the app mechanism that we used w/ that file mostly just provides some additional flexibility / functionality that we don't actually use so the style.css should cover it I think.