[Mailer][Sendgrid] Add support for global region (api transport)

Author: sonnymilton

src/Symfony/Component/Mailer/Bridge/Sendgrid/Tests/Transport/SendgridApiTransportTest.php

@@ -43,6 +43,10 @@ public static function getTransportData()
                 new SendgridApiTransport('KEY', null, null, null, 'eu'),
                 'sendgrid+api://api.eu.sendgrid.com',
             ],
+            [
+                new SendgridApiTransport('KEY', null, null, null, 'global'),
+                'sendgrid+api://api.sendgrid.com',
+            ],
             [
                 (new SendgridApiTransport('KEY'))->setHost('example.com'),
                 'sendgrid+api://example.com',

src/Symfony/Component/Mailer/Bridge/Sendgrid/Transport/SendgridApiTransport.php

@@ -199,7 +199,7 @@ private function getAttachments(Email $email): array
     private function getEndpoint(): ?string
     {
         $host = $this->host ?: str_replace('%region_dot%', '', self::HOST);
-        if (null !== $this->region && null === $this->host) {
+        if (null !== $this->region && 'global' !== $this->region && null === $this->host) {
             $host = str_replace('%region_dot%', $this->region.'.', self::HOST);
         }