Always inline static data in every row of query results that selected a static column

[jleibs]

This could either fully replace #7667 as the default behavior, or alternatively complement through introduction of a static = INLINE configuration option.

Motivation

When static data is included in a query result, it ends up in a special row 0 with null index values. Users need to know to either use LatestAt in their query, or know to combine the static data from row 0 with the data from other columns.

However the general understanding of static data is actually somewhat distinct from the concept of logging data at TimeInt::MIN and then joined via LatestAt.

I believe we have semantically suggested that this data should act equivalent to a constant value across all time and all timelines. By that interpretation, Static data should NOT require a LatestAt join. It should just be there regardless of the index or TimeInt you use to query.

Proposal

• Never include a separate row 0 with static results.
• When a Column is selected that corresponds to static data, include that same data in every row we return.
• Add an additional helper: .select_static() that always returns a single row result with any static data columns.

Benefits

• More intuitive behavior for new users.
• No special handling of row 0
• Returned Index column never has nulls

Disadvantages

• Data duplication for users that don't know whey are working with static data
  • Static data can sometimes be used for large things like maps. If .select() includes static columns, the user could end up inadvertently creating situations where they run out of memory.