Adds the following APIs which are direct reciprocals of the existing
time conversion functions:

OS_time_t OS_TimeFromTotalSeconds(int64 tm)
OS_time_t OS_TimeFromTotalMilliseconds(int64 tm)
OS_time_t OS_TimeFromTotalMicroseconds(int64 tm)
OS_time_t OS_TimeFromTotalNanoseconds(int64 tm)

Instantiate the condvar lock on rtems and vxworks even though the
feature is not currently implemented.  This is because OS_MAX_CONDVARS
must still be nonzero and if the "Create" function is called, it still
goes through the motions of allocating an ID.

This also adds a NULL check in the lock implementation, and thus if a
lock is not instantiated in the future this will not dereference a NULL
pointer.

Adds optional "install" commands to CMake script, which is useful when
building OSAL as a standalone software package.  The public API and
static libraries will be installed to the specified system location, and
can then be used to compile and link external OSAL applications without
the need for the original OSAL source or build trees.

Note this also installs the "osconfig.h" file as this does affect the
binary formats of some items (i.e. size of items using OS_MAX_API_NAME
and other similar structure members).  The external application must be
compiled using the same osconfig.h after installation.

Fix #1304, locks for condvar objects on rtems/vxworks

Fix #1307, Add time conversion reciprocal functions

Fix #1284, add export targets and package script

Fix #1305, Stop empty function catching CI workflow format checks

…ine-cleanup

Fix #1308, Remove redundant/inconsistent comments (/* end of function */, /* end if */ etc.) and clean up empty lines.