Store table row size in system table

[joshua-spacetime]

Ideally this would be a column in st_table, but I don't think we want to change the schema of st_table. It could also be a view over st_columns, but in that case we'd need to add an index to st_columns. The fastest, in terms of deriving the row size, is probably just to store it in a new system table. Perhaps the same one as #1158.

[cloutiertyler]

NOTE: This is presumably only the fixed len portion of the row?

[Shubham8287]

Should we have ST_STATS for storing row size, row count, etc about a table?

[joshua-spacetime]

NOTE: This is presumably only the fixed len portion of the row?

Correct, specifically the BFLATN size.

Should we have ST_STATS for storing row size, row count, etc about a table?

Yes I think so.