`dolt_schema_diff`, `dolt_patch` need better support for `CREATE, ALTER TABLE` statements

MySQL `CREATE TABLE` statements can include schema elements e.g. indexes that Postgres statements cannot. Currently we simply omit these elements when generating the `CREATE TABLE` statements for Doltgres tables. But this means that the output of `dolt_schema_diff` and `dolt_patch` are incomplete for doltgres.

The simplest solution is probably to converge on the postgres restrictions, so that we emit `CREATE TABLE` and `ALTER TABLE` statements that make sense for both dialects.