scripts: module: support for name field in zephyr/module.yml

The folder name of a Zephyr module is also used as its module name
when integrating it into the build system.

This means that a Zephyr module, BAR, located in:
<workspace>/modules/foo
                    |--- zephyr
                          |--- CMakeLists.txt
                          |--- Kconfig

will be referred to as FOO in the build system, that is:
ZEPHYR_FOO_MODULE_DIR==<workspace>/modules/foo
ZEPHYR_FOO_CMAKE_DIR==<workspace>/modules/foo/zephyr

The `name` field allows the module to specify its module name,
independent of its location like:

<workspace>/modules/foo/zephyr/module.yml
```
name: bar
build:
  cmake: zephyr
```

will instead be referred to as BAR in the build system, that is:
ZEPHYR_BAR_MODULE_DIR==<workspace>/modules/foo
ZEPHYR_BAR_CMAKE_DIR==<workspace>/modules/foo/zephyr

This allows for greater flexibility of relocating Zephyr modules in
other folders and at the same time be guaranteed that other modules
depending on `ZEPHYR_BAR_MODULE_DIR` is still working.

If `name` field is not specified in `module.yml`, then the existing
behavior of using the folder name will be used.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>