Replace asset & attribute select dropdowns with or-attribute-picker component.

[dominiquekleeven]

Closes #53 and #52

Changes

This PR replaces the current method of selecting assets and their attributes (dropdowns) with the or-attribute-picker component.

• Added or-attribute-picker dependency.
• Added custom-asset-attribute-picker.ts, which extends/overrides OrAssetAttributePicker.
  • Reasoning: for regressors, we only want to show attributes that have both storeDataPoints and either hasPredictedDataPoints or hasAgentLink meta items.
  • This resolves issue Bug: Attributes without forecasted/predicted datapoints are listed when adding a prophet regressor #52.
• Updated the manager config eventProviderType to WEBSOCKET so that the or-asset-tree component inside the attribute picker functions correctly, as it relies on WebSockets.
• The service now locally updates the manager.displayRealm so that or-asset-tree knows which realm to query for assets.

Screenshots

Select target button

Select attributes dialog (attribute picker)

When an attribute has been selected

Clicking on the Asset/Attribute will show the dialog again to modify it

Regressors

Functions the same as the target, but has an extra meta item requirement for the attribute