Add user blocking (#29028)

Fixes #17453

This PR adds the abbility to block a user from a personal account or
organization to restrict how the blocked user can interact with the
blocker. The docs explain what's the consequence of blocking a user.

Screenshots:


![grafik](https://github.com/go-gitea/gitea/assets/1666336/4ed884f3-e06a-4862-afd3-3b8aa2488dc6)


![grafik](https://github.com/go-gitea/gitea/assets/1666336/ae6d4981-f252-4f50-a429-04f0f9f1cdf1)


![grafik](https://github.com/go-gitea/gitea/assets/1666336/ca153599-5b0f-4b4a-90fe-18bdfd6f0b6b)

---------

Co-authored-by: Lauris BH <lauris@nix.lv>

services/user/user.go

@@ -188,7 +188,7 @@ func DeleteUser(ctx context.Context, u *user_model.User, purge bool) error {
 				break
 			}
 			for _, org := range orgs {
-				if err := models.RemoveOrgUser(ctx, org.ID, u.ID); err != nil {
+				if err := models.RemoveOrgUser(ctx, org, u); err != nil {
 					if organization.IsErrLastOrgOwner(err) {
 						err = org_service.DeleteOrganization(ctx, org, true)
 						if err != nil {