CSS text-align: extend test and update support

[husseinalhammad]

This PR extends the test for the CSS text-align property to include the match-parent value and the vendor-prefixed value -webkit-match-parent.

Summary:

• Some email clients went from full support to partial support
• Gmail iOS/Android now supports flow-relative values start and end
• Some tests were conducted on real devices

Email clients that have not been re-tested:

• New Outlook Windows
• GMX mobile apps
• Web.de mobile apps
• 1&1
• Hey
• Orange
• Fastmail
• Proton Mail
• SFR
• LaPoste