API refactoring: move the query() function

[szkiba]

Currently, the query() function is at the module level and expects the database handle as the first parameter.

function query(db Database, query: string, ...args: any[]): Row[];

interface Database {
  exec(query: string, ...args: any[]): Result;
  close(): void;
}

The query() function should be a member function of the database handle object, similarly to the exec() function.

interface Database {
  exec(query: string, ...args: any[]): Result;
  query(query: string, ...args: any[]): Row[];
  close(): void;
}