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>

templates/user/settings/blocked_users.tmpl

@@ -0,0 +1,5 @@
+{{template "user/settings/layout_head" (dict "ctxData" . "pageClass" "user settings blocked_users")}}
+	<div class="user-setting-content">
+		{{template "shared/user/blocked_users" .}}
+	</div>
+{{template "user/settings/layout_footer" .}}

templates/user/settings/navbar.tmpl

@@ -13,6 +13,9 @@
 		<a class="{{if .PageIsSettingsSecurity}}active {{end}}item" href="{{AppSubUrl}}/user/settings/security">
 			{{ctx.Locale.Tr "settings.security"}}
 		</a>
+		<a class="{{if .PageIsSettingsBlockedUsers}}active {{end}}item" href="{{AppSubUrl}}/user/settings/blocked_users">
+			{{ctx.Locale.Tr "user.block.list"}}
+		</a>
 		<a class="{{if .PageIsSettingsApplications}}active {{end}}item" href="{{AppSubUrl}}/user/settings/applications">
 			{{ctx.Locale.Tr "settings.applications"}}
 		</a>