Duplicate dashboard files when moved to a new folder

[beasteers]

Grizzly Version

0.7.1

Expected Behavior

If you pull dashboards from an instance, move the dashboard to a new folder, then pull the dashboards again, the dashboard should be moved to the new local folder.

$ grr pull "grafana/resources/Main Org"

$ ls grafana/**/dashboard-64nrElFmk.yaml
'grafana/resources/Main Org/dashboards/general/dashboard-64nrElFmk.yaml'

# (Move dashboard in Grafana)

$ grr pull "grafana/resources/Main Org"

$ ls grafana/**/dashboard-64nrElFmk.yaml
'grafana/resources/Main Org/dashboards/cecrsfx5y6q68e/dashboard-64nrElFmk.yaml'

Actual Behavior

Instead, due to the fact that grizzly doesn't delete dashboards, both dashboard files remain.

$ grr pull "grafana/resources/Main Org"

$ ls grafana/**/dashboard-64nrElFmk.yaml
'grafana/resources/Main Org/dashboards/general/dashboard-64nrElFmk.yaml'

# (Move dashboard in Grafana)

$ grr pull "grafana/resources/Main Org"

$ ls grafana/**/dashboard-64nrElFmk.yaml
'grafana/resources/Main Org/dashboards/cecrsfx5y6q68e/dashboard-64nrElFmk.yaml'
'grafana/resources/Main Org/dashboards/general/dashboard-64nrElFmk.yaml'

This may be related to #557, #580

To fix this, when reconciling files, you should load an index like

{
    "dashboard-64nrElFmk": "grafana/resources/Main Org/dashboards/cecrsfx5y6q68e/dashboard-64nrElFmk.yaml"
}

and use that to prevent duplicate files.

Steps to Reproduce

$ grr pull "grafana/resources/Main Org"
$ ls grafana/**/dashboard-64nrElFmk.yaml

# (Move dashboard in Grafana)
$ grr pull "grafana/resources/Main Org"
$ ls grafana/**/dashboard-64nrElFmk.yaml