Add support for Firewatch base config

[oharan2]

For occurring steps and workflows in our project, we want to initialize a source that holds our Firewatch base config.

Once set up (optional), our Openshift-ci env FIREWATCH_CONFIG values will be added on top of that.

This PR allows the user to override the base config by:

• replacing steps with general patterns with specific step names and vice versa
• updating existing rules with new logic.

For example:
The team consistently uses the rule {"step": "failure", "ignore": "True"...} and holds it in their base config file; a specific scenario might need to override it and set the "ignore" to "False".
in this case, the scenario will mention this step in their FIREWATCH_CONFIG env var.

Unit-tests main additions:

• steps containing patterns and steps that matches them are co-existing when configured on the same config data
• config data collected from both base config and additional logic from env var is functioning well

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[oharan2]

/wip

[oharan2]

Pending the merge of #193

[oharan2]

/wip cancel

[oharan2]

/verified

[oharan2]

/verified

[oharan2]

/verified

[calebevans]

/lgtm