[NTOS:CM] Adapt cmboot.c for usage in NT/ReactOS bootloader.

[NTOS:CM] Adapt cmboot.c for usage in NT/ReactOS bootloader.

- Add a new cmboot.h header to isolate the boot-support definitions
  shared with the NT/ReactOS bootloader.

- Move CmpFreeDriverList() to cmboot.c so that we can use it for
  cleanup paths in the NT/ReactOS bootloader.

- CmpFindControlSet(): Directly build the control set name in UNICODE,
  instead of doing an ANSI->UNICODE conversion.

- Directly assign the CurrentControlSet\Services constant string,
  instead of going the route of init-empty-string + append-string.
  This is possible since that string is not modified later.

- Remove ASSERT(FALSE), replacing them with correct failure handling.

- Add cleanup paths in CmpAddDriverToList().

- Simplify and fix CmpFreeDriverList(): it's the full DriverNode
  that needs to be freed; not the LIST_ENTRY pointer.

- Add other validity checks:
  * Registry value types and data sizes;
  * For multi-strings, verify that they are NULL-terminated.
  * For (multi-)strings, check whether they are NULL-terminated before
    optionally removing their trailing NULL character from the count.
    Check also whether they are of zero-length and take appropriate
    action where necessary.

- Add CmpIsDriverInList() for future usage in CMBOOT compiled in
  bootloader mode.

- Add SAL annotations and Doxygen documentation.

- Add debug traces.

- Formatting / code style fixes.

** TODO: Fix SafeBoot support **