Add eslint-plugin-custom-elements (go-gitea#23991)

Add
[eslint-plugin-custom-elements](https://github.com/github/eslint-plugin-custom-elements)
and enable all rules that I've found sensible.

.eslintrc.yaml

@@ -13,6 +13,7 @@ plugins:
   - eslint-plugin-import
   - eslint-plugin-jquery
   - eslint-plugin-sonarjs
+  - eslint-plugin-custom-elements
 
 env:
   es2022: true
@@ -62,6 +63,19 @@ rules:
   consistent-this: [0]
   constructor-super: [2]
   curly: [0]
+  custom-elements/expose-class-on-global: [0]
+  custom-elements/extends-correct-class: [2]
+  custom-elements/file-name-matches-element: [0]
+  custom-elements/no-constructor: [2]
+  custom-elements/no-customized-built-in-elements: [2]
+  custom-elements/no-dom-traversal-in-attributechangedcallback: [2]
+  custom-elements/no-dom-traversal-in-connectedcallback: [2]
+  custom-elements/no-exports-with-element: [2]
+  custom-elements/no-method-prefixed-with-on: [2]
+  custom-elements/no-unchecked-define: [0]
+  custom-elements/one-element-per-file: [0]
+  custom-elements/tag-name-matches-class: [2]
+  custom-elements/valid-tag-name: [2]
   default-case-last: [2]
   default-case: [0]
   default-param-last: [0]

package.json

@@ -59,6 +59,7 @@
     "@stoplight/spectral-cli": "6.6.0",
     "@vitejs/plugin-vue": "4.1.0",
     "eslint": "8.37.0",
+    "eslint-plugin-custom-elements": "0.0.7",
     "eslint-plugin-import": "2.27.5",
     "eslint-plugin-jquery": "1.5.1",
     "eslint-plugin-sonarjs": "0.19.0",