[Debug UI] ESLint and Prettier for the debug UI code. (near#8594)

Also corrects all the code that violates any issues found by ESLint and Prettier.

tools/debug-ui/.eslintrc.yml

@@ -0,0 +1,32 @@
+env:
+  browser: true
+  es2021: true
+extends:
+  - eslint:recommended
+  - plugin:react/recommended
+  - plugin:react/jsx-runtime
+  - plugin:@typescript-eslint/recommended
+  - plugin:import/recommended
+  - plugin:import/typescript
+  - prettier
+overrides: []
+parser: '@typescript-eslint/parser'
+parserOptions:
+  ecmaVersion: latest
+  sourceType: module
+plugins:
+  - react
+  - '@typescript-eslint'
+rules:
+  import/order:
+    - error
+  "@typescript-eslint/no-non-null-assertion":
+    - off
+  "@typescript-eslint/no-unused-vars":
+    - error
+settings:
+  import/resolver:
+    typescript: true
+    node: true
+  react:
+    version: detect

tools/debug-ui/.prettierrc.json

@@ -0,0 +1,6 @@
+{
+    "printWidth": 100,
+    "tabWidth": 4,
+    "singleQuote": true,
+    "bracketSameLine": true
+}

tools/debug-ui/README.md

@@ -39,3 +39,9 @@ same keys are only fetched once.
 It's also helpful to understand at a high level how the react-router library works; this is used
 to support deep-linking in the URL (e.g. `/127.0.0.1/cluster` leads to the cluster page), allowing
 the UI to be served as a single application.
+
+### Linting & Formatting
+The project is configured to use ESLint (error-checking) and Prettier (consistent formatting).
+
+Run `npm run lint` to check for linting & formatting errors, and `npm run fix` to fix those that
+can be automatically fixed.