ENH: Rename ALL_MODULES to DEFAULT_MODULES

This renames the CMake option ITK_BUILD_ALL_MODULES to
ITK_BUILD_DEFAULT_MODULES. This also renames CMake itk_module() macro
argument EXCLUDE_FROM_ALL to EXCLUDE_FROM_DEFAULT.

"ALL_MODULES" suggests a set that includes all modules that are known to
ITK, but this is not the actual behavior. A more descriptive name for the
standard set of modules is "DEFAULT_MODULES".

A migration guide is included. Any build configurations that use the
ITK_BUILD_ALL_MODULES option should be updated. Any Remote or External
ITK modules that use the EXCLUDE_FROM_ALL argument in their module
definition file should be updated. Using the old option / argument will
still function, but will generate a helpful CMake warning.

Authors:
Brian Helba <brian.helba@kitware.com>
Xiaoxiao Liu <xiaoxiao.liu@kitware.com>

Change-Id: Ib07028b5ab6c4ff67a1dfb73dcacce7f2fecbb9b
Merge topic 'DeprecateITK_BUILD_ALL_MODULES'

0a98a97 ENH: Rename ALL_MODULES to DEFAULT_MODULES
STYLE: Extract module dependency code to a separate file.

For maintenance purpose.

Change-Id: I018bcacd91850b0905c497fdbf8ebf4548a787fc
Merge topic 'ImprovingCustomizingModules'

831d6a7 STYLE: Extract module dependency code to a separate file.