Show if commit is signed in activity feed and unify sha box (#6933)

Old activities are shown like before, new commits are displayed like commits in e.g. the commits list. _(Second commit)_

| New signed commits | Old (signed) commits |
|:--:|:--:|
| ![image](/attachments/cd81c761-eda6-44bf-8c43-ac3b7e6f16eb) | ![image](/attachments/243080f3-1b77-4ca7-bc03-bbf855c39c99) |

Additionally the sha box was moved in an own component to unify the usage. _(First commit)_

Closes #1824

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- User Interface features
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/6933): <!--number 6933 --><!--line 0 --><!--description U2hvdyBpZiBjb21taXQgaXMgdmVyaWZpZWQgaW4gYWN0aXZpdHkgZmVlZCBvZiBhbiB1c2VyIG9yIGFuIG9yZ2FuaXphdGlvbiBmb3IgbmV3IGFjdGl2aXR5-->Show if commit is verified in activity feed of an user or an organization for new activity<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6933
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Beowulf <beowulf@beocode.eu>
Co-committed-by: Beowulf <beowulf@beocode.eu>

services/repository/files/commit.go

@@ -1,4 +1,5 @@
 // Copyright 2019 The Gitea Authors. All rights reserved.
+// Copyright 2025 The Forgejo Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
 package files
@@ -38,7 +39,7 @@ func GetPayloadCommitVerification(ctx context.Context, commit *git.Commit) *stru
 	verification.Verified = commitVerification.Verified
 	verification.Reason = commitVerification.Reason
 	if verification.Reason == "" && !verification.Verified {
-		verification.Reason = "gpg.error.not_signed_commit"
+		verification.Reason = asymkey_model.NotSigned
 	}
 	return verification
 }