Support writing progress as JSON

[anmenaga]

PR Summary

Fix #592

1. This adds writing json progress messages to STDERR stream if -f, --format argument to dsc.exe is json or pretty-json.
2. Fixed a bug with Searching for adapted resources progress which previously was always showing 0.

The structure of json progress message is following. activity and percent_complete are expected to always have value; the rest of the fields are optional.
Same structure will be expected from resources when they will want to provide progress status to dsc (this support will be implemented soon).

pub struct DscProgressValue {
    pub activity:  String,
    pub status: String,
    pub percent_complete: u16,
    pub seconds_remaining: u64,
}

Dev notes:

1. Added struct DscProgressBar which is wrapping both UI progress bar and json serialization;
2. moved pub enum OutputFormat from dsc to dsc_lib and updated all references.

[SteveL-MSFT]

instead of comparing text, since all output should be JSON, you should convert every line from json and check the object

[SteveL-MSFT]

same here, use convertfrom-json