build(deps-dev): remove package rollup-plugin-license (#1796)

The `rollup-plugin-license` has been using too many deprecated dependencies, so it is necessary to remove it.

As an alternative, this changes uses Rollup `output.banner` to insert copyright information. Since `terser` runs after `output`, it is not possible to insert the Front Matter defining permlink for `sw.js` through the same way (Jekyll Front Matter is YAML rather than JS, which would cause errors with terser).

Therefore, _Jekyll Collection_ is now used to add permlink to `sw.js`, with the collection named `app`, and the directory placed in `_app`. This directory is not tracked by git, but it will be included when building the gem.

_config.yml

@@ -168,6 +168,9 @@ collections:
   tabs:
     output: true
     sort_by: order
+  app:
+    output: true
+    permalink: /:name
 
 defaults:
   - scope:
@@ -190,10 +193,6 @@ defaults:
     values:
       layout: page
       permalink: /:title/
-  - scope:
-      path: assets/js/dist
-    values:
-      swcache: true
 
 sass:
   style: compressed