Site reorg: Remove site/ subpath (#306)

Unfortunately, for proper package pathing, need to remove the `site/`
subpath. This includes:
- Moving everything back into root
- Adding a `copy-site.sh` script to copy resources into `mkdocs/site/`
before building the site with mkdocs.
- Also update examples to ensure all are loading the local sw.js / ui.js
- Consolidate examples in `docs/examples`
- Consolidate assets under src/assets/
- Move `favicons` to root
- Reformat and relint
- Tests: update playwright tests to use mkdocs output, add test for
embed in docs
- bump to 2.0.0-beta.2

.gitignore

@@ -1,7 +1,8 @@
+**/sw.js
+**/ui.js
 *.har
 *.warc
 *.warc.gz
-!site/examples/*.warc
 **/node_modules
 yarn-error.log
 coverage/
@@ -9,12 +10,13 @@ coverage/
 **/.DS_Store
 **/.sass-cache/
 **/__pycache__/
-mkdocs/_genhtml/
 dist/
 plugins-*/
-site/sw.js
-site/ui.js
-site/favicons/
-.jekyll-cache
-
+!mkdocs/site/docs/examples/*.warc
+mkdocs/_genhtml/
+mkdocs/site/index.html
+mkdocs/site/embed.html
+mkdocs/site/webmanifest.json
+mkdocs/site/favicons
+mkdocs/site/ruffle
 ipfs-core.min.js