Support for variable autofill for Inline imports of clusters

[on-core]

Currently none of the variables from Table are autofilled with intellisense:

let start = ago(40m);
cluster("https://cluster.kusto.windows.net").database("Database").
Table
| where env_time > start
| take 10

Adding this would make the library extremely powerful as I often use KQL queries against multiple clusters and forwards their results to other queries using cluster.