[#3948] added Bitbucket OAuth2 provider

Co-authored-by: aabajyan <arsen.abajyan@pm.me>

ui/src/providers.js

@@ -59,6 +59,11 @@ export default [
         optionsComponent: SelfHostedOptions,
         optionsComponentProps: { title: "Self-hosted endpoints (optional)" },
     },
+    {
+        key:   "bitbucketAuth",
+        title: "Bitbucket",
+        logo:  "bitbucket.svg",
+    },
     {
         key:   "giteeAuth",
         title: "Gitee",