New shell implementation is on the way. For now old one and all
references are kept to be gradually replaced by new shell.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Add a set of modem shell commands to support modem development.
Start with:
modem list: Lists all registered modems and related information
modem send <modem receiver index> <command>: Send command to modem
Signed-off-by: Michael Scott <mike@foundries.io>