* Start porting to Teensy 4.1, also fix some compiler warnings in FSL HAL

* Add hardware init for Teensy, refactor phy drivers, rework IMX EMAC autonegotiate code

* Revert some testing changes

* Fix incorrect phy address used outside of low_level_init_successful()

* Ethernet operational!

* Turn off DEBUG_IMX_EMAC

* Style fixes

* Style again

* Bugfix: mbed_lib.json files in project source dir were not getting picked up

* Bugfix: CLion debug configurations not generated properly due to variables going out of scope

* Support Teensy OTP MAC address

* Initial attempt at Teensy 4.0 support

* Hide internal target

* Fix some targets.json issues, add boot code for the MIMXRT1060_EVK.  It boots but tests aren't able to run properly yet.

* Disable LPTICKER on MIMXRT1060, fix pin names for newer dev kits

* Enable MIMXRT106x ethernet

Base Functionality, UART, Timers, I2C , SPI, ADC

Refactor all NXP targets to be CMake build system targets. This removes
the need for checking MBED_TARGET_LABELS repeatedly and allows us to be
more flexible in the way we include MBED_TARGET source in the build.

A side effect of this is it will allow us to support custom targets
without breaking the build for 'standard' targets, as we use CMake's
standard mechanism for adding build rules to the build system, rather
than implementing our own layer of logic to exclude files not needed for
the target being built. Using this approach, if an MBED_TARGET is not
linked to using target_link_libraries its source files will not be
added to the build. This means custom target source can be added to the
user's application CMakeLists.txt without polluting the build system
when trying to compile for a standard MBED_TARGET.