Update copyright notice & footer (#2496)

## Description:

* Update copyright notice to "OpenFront and Contributors"

* remove the "how to play" on the footer, since that will be moved to
the death screen.

* Removed css and used tailwind instead for better mobile support


Describe the PR.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/client/styles/layout/footer.css

@@ -1,24 +0,0 @@
-.l-footer {
-  background: var(--boxBackgroundColor);
-  backdrop-filter: blur(var(--blur-md));
-  display: flex;
-  justify-content: center;
-  padding: 12px;
-
-  @media (min-width: 800px) {
-    padding: 12px 24px;
-  }
-}
-
-.l-footer__content {
-  max-width: 860px;
-  flex-wrap: wrap;
-  display: flex;
-  flex: 1;
-  justify-content: space-between;
-}
-
-.l-footer__col {
-  display: flex;
-  gap: 20px;
-}