add admin button to homepage and hamburger-menu

[trstngttschlk]

Description

• added Admin button to homepage linking to adminDashboard
  • used FaUserShield as logo for Admin button
• added Admin link to HamburgerNav linking to adminDashboard
• added Admin button testing to landing.cy.js and tgt.js

Type of change

Please select everything applicable. Please, do not delete any lines.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [ ] This change requires an update to testing

Issue

• [x] Is this related to a specific issue? If so, please specify: closes #405

Checklist:

• [x] This PR is up to date with the main branch, and merge conflicts have been resolved
• [x] I have executed npm run test and all tests have passed successfully or I have included details within my PR on the failure.
• [x] I have executed npm run lint and resolved any outstanding errors. Most issues can be solved by executing npm run format
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings

[Caleb-Cohen]

Howdy! Button looks great!

Everything looks good. One request. Can you add button testing to cypress/e2e/landing.cy.js?

I will want to merge this after we finish #439 so that users do not have access to the menu button.

[trstngttschlk]

Hi Caleb, Added testing for the new admin button. Please let me know if any changes are needed. Thanks.