Remove dependency of go-bindata (#818)

* Use new embed functionality for serving UI assets

* Use new embed functionality for serving resources. Remove dependency on go-bindata

* Remove Go 1.15

resources/embed.go

@@ -0,0 +1,22 @@
+package resources
+
+import (
+	"embed"
+	"io/fs"
+	"io/ioutil"
+)
+
+//go:embed *
+var filesystem embed.FS
+
+func Asset(path string) ([]byte, error) {
+	f, err := filesystem.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	return ioutil.ReadAll(f)
+}
+
+func Assets() fs.FS {
+	return filesystem
+}