move [githubtag] and [githubrelease] under /v, move variants to query params (#3610)

* move GH tag and release under /v, move variants to query params
    - move github /tag and /release under /v
    - both sort by date as default
    - specify sort=date/semver, include_prereleases as query params
    - use graphql api for tags

* pass string params from example defs to modal

frontend/components/customizer/query-string-builder.js

@@ -187,7 +187,7 @@ export default function QueryStringBuilder({
       // Throughout the component, these two types are supported in the same
       // manner: by inspecting this value type.
       const isStringParam = typeof value === 'string'
-      result[name] = isStringParam ? '' : true
+      result[name] = isStringParam ? value : true
     })
     return result
   })