Replace pkger with go:embed for bundling the admin. Closes #844 (#1464)

* Replace pkger with go:embed for bundling the admin. Closes #844

* Remove references to pkged.go

* Point tests to use an updated version of Go

* Add comment to new exported function

* Cleanup

* Add a dummy pkged.go to alert people to stop using it.

* Add simple browser test to make sure the admin is available and renders

* Don't panic

static/static.go

@@ -0,0 +1,14 @@
+package static
+
+import "embed"
+
+//go:embed admin/*
+//go:embed admin/_next/static
+//go:embed admin/_next/static/chunks/pages/*.js
+//go:embed admin/_next/static/*/*.js
+var adminFiles embed.FS
+
+// GetAdmin will return an embedded filesystem reference to the admin web app.
+func GetAdmin() embed.FS {
+	return adminFiles
+}