LibWebView: Add method to remove all cookies globally

The inspector widget has this functionality, but it's limited to the
site you're currently viewing. This commit adds an option for removing
all cookies globally.

Previously, the workaround was to open a sqlite shell and run:
`DELETE FROM Cookies;` on the database yourself.

Libraries/LibWebView/CookieJar.cpp

@@ -174,6 +174,11 @@ void CookieJar::dump_cookies()
     dbgln("{} cookies stored\n{}", m_transient_storage.size(), builder.string_view());
 }
 
+void CookieJar::clear_all_cookies()
+{
+    m_transient_storage.expire_and_purge_all_cookies();
+}
+
 Vector<Web::Cookie::Cookie> CookieJar::get_all_cookies()
 {
     Vector<Web::Cookie::Cookie> cookies;
@@ -639,6 +644,16 @@ UnixDateTime CookieJar::TransientStorage::purge_expired_cookies(Optional<AK::Dur
     return now;
 }
 
+void CookieJar::TransientStorage::expire_and_purge_all_cookies()
+{
+    for (auto& [key, value] : m_cookies) {
+        value.expiry_time = UnixDateTime::earliest();
+        set_cookie(key, value);
+    }
+
+    purge_expired_cookies();
+}
+
 void CookieJar::PersistedStorage::insert_cookie(Web::Cookie::Cookie const& cookie)
 {
     database.execute_statement(

Libraries/LibWebView/CookieJar.h

@@ -48,6 +48,7 @@ class CookieJar {
         size_t size() const { return m_cookies.size(); }
 
         UnixDateTime purge_expired_cookies(Optional<AK::Duration> offset = {});
+        void expire_and_purge_all_cookies();
 
         auto take_dirty_cookies() { return move(m_dirty_cookies); }
 
@@ -91,6 +92,7 @@ class CookieJar {
     void set_cookie(const URL::URL& url, Web::Cookie::ParsedCookie const& parsed_cookie, Web::Cookie::Source source);
     void update_cookie(Web::Cookie::Cookie);
     void dump_cookies();
+    void clear_all_cookies();
     Vector<Web::Cookie::Cookie> get_all_cookies();
     Vector<Web::Cookie::Cookie> get_all_cookies(URL::URL const& url);
     Optional<Web::Cookie::Cookie> get_named_cookie(URL::URL const& url, StringView name);