Blueprint Selector

[vasilvas99]

Since the handling of desired states is now available in Leda and the blueprints concept is in development, we would like to give the user an easy way to switch between blueprints.

In this PR I propose that we expand the desired state messages with additional metadata, describing the to-be deployed blueprint with this desired state.
Additionally, the Rust-based "blueprint selector" presents the user with a nice TUI for fetching/selecting between existing blueprints.

The "blueprint" files are desired state messages, that have the extension ".blueprint.json" (configurable) and an additional metadata header (required):

{
  "blueprintMetadata": {
    "name": "<NAME>",
    "description": "<Short Description>"
  },
  "activityId": "correlation-id",
  "timestamp": 1235466
  "payload": {} // This is the desired state message
}

The metadata header will be used to construct the list of options presented to the user. You can find example blueprints under the
example_blueprints directory.

More information about the operation of the selector can be found in the README.md file.

Test setup

Integration with meta-leda can be found here:
https://github.com/SoftwareDefinedVehicle/meta-leda-fork/tree/blueprint-selector

And an integration with Leda-distro (ready to be build from/tested), here:
https://github.com/SoftwareDefinedVehicle/leda-distro-fork/tree/blueprint-selector

[stlachev]

LGTM