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>

routers/web/web.go

@@ -647,6 +647,11 @@ func registerRoutes(m *web.Route) {
 			})
 			addWebhookEditRoutes()
 		}, webhooksEnabled)
+
+		m.Group("/blocked_users", func() {
+			m.Get("", user_setting.BlockedUsers)
+			m.Post("", web.Bind(forms.BlockUserForm{}), user_setting.BlockedUsersPost)
+		})
 	}, reqSignIn, ctxDataSet("PageIsUserSettings", true, "AllThemes", setting.UI.Themes, "EnablePackages", setting.Packages.Enabled))
 
 	m.Group("/user", func() {
@@ -945,6 +950,11 @@ func registerRoutes(m *web.Route) {
 						m.Post("/rebuild", org.RebuildCargoIndex)
 					})
 				}, packagesEnabled)
+
+				m.Group("/blocked_users", func() {
+					m.Get("", org.BlockedUsers)
+					m.Post("", web.Bind(forms.BlockUserForm{}), org.BlockedUsersPost)
+				})
 			}, ctxDataSet("EnableOAuth2", setting.OAuth2.Enabled, "EnablePackages", setting.Packages.Enabled, "PageIsOrgSettings", true))
 		}, context.OrgAssignment(true, true))
 	}, reqSignIn)