Include missing metas when converting `ExprNode`<->`PartiqlAst`

[alancai98]

In ExprNodeToStatement.kt, we are currently losing some metas when converting from ExprNode to PartiqlAst. This is especially common when converting literals. These metas should be preserved wherever possible.

Should also check going the other way (i.e. PartiqlAst to ExprNode) with StatementToExprNode.kt.

TODO: decide if we should add a testing function to check if all metas are preserved. This could be as simple as taking an ExprNode converting it to PartiqlAst and back to ExprNode then checking for metas equality.