Modify linker scripts to add heap to memory map, add list of supported c libs and "bare-metal" to supported_application_profiles.

The armclang shebang is required in the scatter file in order to build with CMake.

Scancode found missing license notices in our source files. This commit
addresses those issues by adding an Apache-2.0 notice to source files
highlighted.

Workaround a bug where the boot stack size configuration option is not
passed on to armlink, the Arm Compiler's linker. Prefer
MBED_CONF_TARGET_BOOT_STACK_SIZE if present, as this is what the
configuration system should provide. Fall back to MBED_BOOT_STACK_SIZE
if MBED_CONF_TARGET_BOOT_STACK_SIZE is not defined, as in the case of
buggy tools. If both MBED_CONF_TARGET_BOOT_STACK_SIZE and
MBED_BOOT_STACK_SIZE are not defined, then we fall back to a hard-coded
value provided by the linkerscript. See
https://github.com/ARMmbed/mbed-os/issues/13474 for more information.

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

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>

This is a fix for Issue#9254

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>

### Description

The Mbed 2 release was broken for FF_LPC546XX as it would include
the entire mbed 2 build of the LPC546XX. This PR seperates these 2
builds completely by:

 * Removing non-shared extra labels from the MCU_LPC546XX target
 * Moving the target implementation to a shared target directory

### Pull request type

    [x] Fix
    [ ] Refactor
    [ ] Target update
    [ ] Functionality change
    [ ] Breaking change