Tweak stylelint config (#38228)

* rename to .stylelintrc.json
* add reportInvalidScopeDisables to config
* move reportNeedlessDisables to config
* merge the two configs
* remove unneeded disabled rules from the examples config

site/assets/scss/_variables.scss

@@ -1,5 +1,3 @@
-// stylelint-disable scss/dollar-variable-default
-
 // Local docs variables
 $bd-purple:        #4c0bce;
 $bd-violet:        lighten(saturate($bd-purple, 5%), 15%); // stylelint-disable-line function-disallowed-list

site/assets/scss/docs.scss

@@ -28,8 +28,8 @@
 @import "../../../scss/mixins";
 
 // fusv-disable
-$enable-grid-classes: false; // stylelint-disable-line scss/dollar-variable-default
-$enable-cssgrid: true; // stylelint-disable-line scss/dollar-variable-default
+$enable-grid-classes: false;
+$enable-cssgrid: true;
 // fusv-enable
 @import "../../../scss/grid";
 

site/content/docs/5.3/examples/.stylelintrc

@@ -1,15 +0,0 @@
-{
-  "extends": [
-    "stylelint-config-twbs-bootstrap"
-  ],
-  "rules": {
-    "at-rule-no-vendor-prefix": null,
-    "comment-empty-line-before": null,
-    "media-feature-name-no-vendor-prefix": null,
-    "property-disallowed-list": null,
-    "property-no-vendor-prefix": null,
-    "selector-no-qualifying-type": null,
-    "selector-no-vendor-prefix": null,
-    "value-no-vendor-prefix": null
-  }
-}