[HUE-7468] [assist] Convert collection assist into tree mode - Cloudera Open Source

Details

Progress

1.	[assist] Improve icons and i18n for the collections panel	Resolved	Enrico Berti
2.	[assist] Wire in the right sample popup for the collections items	Resolved	Enrico Berti
3.	[assist] Update the context menu for the collections items	Resolved	Enrico Berti
4.	[assist] Pre-select the source and root item for the collections panel	Resolved	Enrico Berti
5.	[assist] Re-use the new collections panel on the dashboard right assist	Resolved	Enrico Berti
6.	[assist] Create index from the Solr assist	Resolved	Enrico Berti
7.	[assist] Hide filter icon from the Solr assist	Resolved	Enrico Berti
8.	[assist] List collections aliases on the Solr assist	Resolved	Romain Rigaux
9.	[assist] Avoid fetching the top columns for the collections panel	Resolved	Enrico Berti
10.	[assist] Split the column entry assist for the right assistant	Resolved	Enrico Berti
11.	[assist] Remove unused AssistCollectionEntry references	Resolved	Enrico Berti