git: add realName inside From field

We currently have no way of specifying the sender's name inside the
From field, making a patch sent through `git send-email` appear as
coming from "xxx@domain.com".

In this commit we make this field follow the standard

    realName <email>

format.

tests/modules/programs/git/git-with-email-expected.conf

@@ -1,12 +1,12 @@
 [sendemail "hm-account"]
-	from = "hm@example.org"
+	from = "H. M. Test Jr. <hm@example.org>"
 	smtpEncryption = "tls"
 	smtpServer = "smtp.example.org"
 	smtpSslCertPath = "/etc/test/certificates.crt"
 	smtpUser = "home.manager.jr"
 
 [sendemail "hm@example.com"]
-	from = "hm@example.com"
+	from = "H. M. Test <hm@example.com>"
 	smtpEncryption = "ssl"
 	smtpServer = "smtp.example.com"
 	smtpSslCertPath = "/etc/ssl/certs/ca-certificates.crt"