moat: support meek and meek-azure transports

In moat currently meek is being called meek-azure even thought it is not using azure anymore. We are going to rename it meek (tpo/applications/tor-browser#43816 (moved)).

For backward compatibility for the time being we are going to support both names. So moat/circumvention settings APIs will accept and provide both meek and meek-azure, so old clients are supported and have an upgrade path.

The affected endpoints are:

• /circumvention/settings
  • request transport
  • response "settings": {"type": ...}
• /circumvention/defaults (currently doesn't provide meek)
  • request transport
  • response "settings": {"type": ...}
• /circumvention/map
  • response "settings": {"type": ...}
• /circumvention/builtin
  • response duplicated for meek and meek-azure

Tasks needed:

• reading builtin bridges accept meek and meek-azure and create the other one if missing
• duplicate the options in the circumvention map
• set a deprecation date for meek-azure so we can delete the hacky code that duplicates it