Parameterize `QueryExpr` storing actual values in a separate list

[Centril]

Like how we extracted out the sources with SourceSet, we should extract e.g., 42 in a query SELECT * FROM bar WHERE bar.id = 42 and instead insert a symbolic pointer, ParamId(0).

This will allow us to reuse queries even more and cache them, as well as adding prepared statements.

[Centril]

This is part of https://github.com/clockworklabs/SpacetimeDB/issues/1089.