Add strings to accepted fields for Insights Panel "Metrics"

[jamescammarano]

Add strings to accepted fields for Insights Panel "Metrics"
Before this PR:

• The insights dashboard had a metrics panel that allowed aggregation of a field. It only accepted numbers though.
• The panel-configuration used v-form to display options.
• the index.ts for the PanelConfig only took objects.
• metrics.vue only displayed numbers.
• The field-configuration passed a function to an extensions-options component.

Now:

• field-configuration passes an object to extensions-options
• extension-options takes an object not a function
• The PanelConfig interface has a property for alterOptions which is a function that returns an altered Panel object. In the case of metrics the fields are altered to display different choices.
• panel-configuration uses extension-options to display the fields available and allows props.panel.alterOptions() to change any display property.
• metrics/index.ts contains a function that removes the choices from the function field.
• metrics.vue takes NaN for display values.

TODO:

• Load the current options when editing a panel
• Reset values when collection changes
• clear values when selected panel configuration changes (EX: metric to list)
• Configure all of the panels that use extension-options to work with the new changes

Future-Proofing:
I added an optional property to the PanelConfig interface to allow a function that manipulates what the edits object contains. I pass the whole panel edits object to the panel from panel-configuration. This will allow future panels to use the alterOptions function to change more than just what fields are available.

Preview:

[rijkvanzanten]

@jaycammarano Is this still a (WIP) as the title suggests?

[jamescammarano]

@jaycammarano Is this still a (WIP) as the title suggests?

no

[rijkvanzanten]

I'll handle the review points 👍🏻