Mirror anti-censorship projects from gitweb to gitlab

Let's create some mirrors for our more popular anti-censorship projects that will collect pull requests. Some projects like GetTor are already mirrored.

The ones we still need to tackle are:

• https://gitweb.torproject.org/pluggable-transports/snowflake.git/
• https://gitweb.torproject.org/pluggable-transports/snowflake-webext.git/
• https://gitweb.torproject.org/pluggable-transports/snowflake-mobile.git/

Any others?