Feat: Add Basic Lua Test Suite (#115)

This MR adds a Lua test suite to the project, run via busted, and introduces tests for a number of the utility functions. Subsequent work will have to be done to test functions that use the `vim.api` scope and external packages to the plugin.

.github/workflows/lua-tests.yaml

@@ -0,0 +1,15 @@
+name: Lua Tests
+on:
+  pull_request:
+    branches:
+      - main
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Run Busted
+        uses: lunarmodules/busted@v2.2.0
+        # with:
+        #     args: --run=api