Added foundation of command line interface argument/flag parsing/handling

[jhodapp]

Added the use of the crate clap for command line interface argument/flag parsing.

Clap reference

Provides -d|--debug, -V|--version and -h|--help with this changeset.

Refer to the ambi_mock_client CLI design document for more background info.

Also sets the foundation for separation of application logic now being in lib.rs instead of everything being in main.rs. See the Rust book section 12.3 for more info.

Example output

$ ambi_mock_client --help
Ambi Mock Client 0.1.0
Rust Never Sleeps community (https://github.com/Jim-Hodapp-Coaching/)
This application emulates a real set of hardware sensors that can report on environmental conditions
such as temperature, pressure, humidity, etc.

USAGE:
    ambi_mock_client [OPTIONS]

OPTIONS:
    -d, --debug
            Turns verbose console debug output on

    -h, --help
            Print help information

    -V, --version
            Print version information

or setting verbose debug output on:

$ ambi_mock_client -d
Debug mode is now *on*

cli: Cli { debug: true }

Sending POST request to http://localhost:4000/api/readings/add as JSON: {"temperature":"24.2","humidity":"70.1","pressure":"960","dust_concentration":"999","air_purity":"High Pollution"}
Response: Ok(
    Response {
        url: Url {
            scheme: "http",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: Some(
                Domain(
                    "localhost",
                ),
            ),
            port: Some(
                4000,
            ),
            path: "/api/readings/add",
            query: None,
            fragment: None,
        },
        status: 200,
        headers: {
            "cache-control": "max-age=0, private, must-revalidate",
            "content-length": "60",
            "content-type": "application/json; charset=utf-8",
            "date": "Thu, 31 Mar 2022 20:17:33 GMT",
            "server": "Cowboy",
            "x-request-id": "FuF_EewOgIHT5BkAAEfn",
        },
    },
)

Closes #5

[glynos]

Clap looks like an interesting utility! LGTM

[jhodapp]

Clap looks like an interesting utility! LGTM

Indeed, I was pleasantly surprised to find this while searching around. I started down the path of the Rust Book's CLI handling but then stumbled upon clap. I'm very impressed with its developer interface.

[jhodapp]

@calebbourg thanks for the review!