The CMake macro `mbed_post_build_psoc6_merge_hex()` takes the name of
a Cypress target and an optional Cortex-M0 hex image as arguments. The
proper way to define and parse optional arguments of a function or
macro is `cmake_parse_arguments()`, which allows the caller to
indicate what they are passing rather than rely on an argument's
relative position within `${ARGN}` which is not rigorous.

Also, avoid duplicating the common part of the post build command
when the optional argument is passed/not passed.

- list files included via module path
- <project-name>_SOURCE_DIR for sources that are out of the current processed CMake
- CMAKE_CURRENT_LIST_DIR for listfiles

The CMake custom target must be unique to avoid more than one
Mbed target adding the same. Only the CMake custom command added for the
Mbed target being built is run as the custom CMake target now includes
the Mbed target name.

Refactor all Cypress targets to be CMake buildsystem 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.

A CMake custom target, mbed-post-build, is added as a dependency of the
application CMake target if a Mbed target adds a CMake custom target
named mbed-post-build-bin. mbed-post-build-bin is added as a dependency
of mbed-post-build. mbed-post-build-bin depends on the application binary.
This is done so a CMake custom command that executes post-build can be added.

The Python scripts that implement the operations have been modified to add
CLI entry points so they can be called from CMake. Dependency on the old
tool has been removed on those scripts by passing them exactly what they
require instead of passing old tool Python objects. A consequence of that
was to slightly amend how the old tool calls some of those Python modules.

Support has only been added for Mbed targets that currently have a requirement
for post build operations. This includes: LPC1114, LPC1768, ARCH_PRO, LPC54114,
LPC546XX, FF_LPC546XX, CY8CKIT064B0S2_4343W, CYTFM_064B0S2_4343W, CYSBSYSKIT_01

The following targets are not supported as TFM support is not yet included:
ARM_MUSCA_B1, ARM_MUSCA_B1_NS, ARM_MUSCA_S1, ARM_MUSCA_S1_NS.

In some toolchains, in order to use linker symbols referring to the
start and end of a region, the region name must not contain a '.'
character. These changes allow those symbols to be used for the cy_xip
region by renaming it. They also create explicit start and end symbols
for GCC.

To allow overriding of the boot stack size from the Mbed configuration
system, consistently use MBED_CONF_TARGET_BOOT_STACK_SIZE rather than
MBED_BOOT_STACK_SIZE.

Fixes #10319