meson: rename libudev_internal to libudev_static and link into libudev

meson: rename libudev_internal to libudev_static and link into libudev

This reduces the meson man=false target count to 1281.

v2:
- link test-engine with libshared instead of libsystemd_static
Previous version built fine on F27, but fails on F26 with the following error:
/usr/bin/ld: /tmp/ccr8HRGw.ltrans6.ltrans.o: undefined reference to symbol '__start_BUS_ERROR_MAP@@SD_SHARED'
/home/zbyszek/fedora/systemd/systemd-9d5aae75c64f5583a110f03b94816aacc03bbf4d/x86_64-redhat-linux-gnu/src/shared/libsystemd-shared-236.so: error adding symbols: DSO missing from command line

v3:
- add libudev_basic