Add navbar-buttons style to tamu theme navbar override

[wwelling]

References

Resolves #23

Description

Update styles for TAMU theme navbar override.

Instructions for Reviewers

From this branch, update config to labs DSpace REST API as follows.

rest:
  ssl: true
  host: api-dev.library.tamu.edu
  port: 443
  nameSpace: /dspace7

Start in development mode.

yarn start:dev

Make sure the navbar right content does not stack.

Checklist

This checklist provides a reminder of what we are going to look for when reviewing your PR. You need not complete this checklist prior to creating your PR (draft PRs are always welcome). If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• [x] My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• [x] My PR passes ESLint validation using yarn lint
• [x] My PR doesn't introduce circular dependencies (verified via yarn check-circ-deps)
• [ ] My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• [ ] My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• [ ] If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• [ ] If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• [ ] If my PR fixes an issue ticket, I've linked them together.