Add support for ARRAY_TO_STRING()

[prrao87]

Migrating this request from @bigluck: in many cases, it is useful to join a list of strings into a string.

Description

In my case, I have an Artifact - [ShouldHaveColumn] -> artifact_col:ArtifactColumn - [IsInputColumnOf] -> Fn
// (ShouldHaveColumn) because the user has defined the column in its code, but there is no guarantee that columns exist for real.

While preparing my graph, I would like to store the list of all the column names in a field of type string.

The only way I found is by doing: CAST(scan_columns, 'STRING')
However, the output string is not in the format I would like [col1, col2, col3]; in my case, I prefer col1, col2, col3.

It would be super helpful to have a function that allows me to specify the list and the separator, as this is a common problem.

Example:

• Snowflake
• Postgres