How is this Antenna Plug Type Called?
These are commonly and informally known as "U.FL connectors" after the original part number from Hirose, see this https://en.wikipedia.org/wiki/Hirose_U.FL. 

It is a proprietary connector from Hirose, but many second source exist, typically under the name "ultraminiature coaxial connector" or similar.

Search for "UFL to SMA".