Generated PostgreSQL migration file does not contain schema SQL

[enylin]

Issue Description

Generated PostgreSQL migration file does not contain schema creation or deletion SQL.

Expected Behavior

Suppose we have the following entity code,

@Entity({ schema: 'my_schema', name: 'my_name' })

the migration file generated should include something like
CREATE SCHEMA my_schema;
and
DROP SCHEMA my_name;

Actual Behavior

nothing

Steps to Reproduce

1. Create an entity file
2. Run node -r ts-node/register ./node_modules/typeorm/cli.js -d data-source.ts migration:generate -n migraion_file

@Entity({ schema: 'my_schema', name: 'my_name' })
export class MyName  {
  // ...
}

My Environment

Dependency	Version
Operating System	Debian 11
Node.js version	v16.17.0
Typescript version	4.8.2
TypeORM version	0.3.9

Additional Context

Relevant Database Driver(s)

DB Type	Reproducible
aurora-mysql	no
aurora-postgres	no
better-sqlite3	no
cockroachdb	no
cordova	no
expo	no
mongodb	no
mysql	no
nativescript	no
oracle	no
postgres	yes
react-native	no
sap	no
spanner	no
sqlite	no
sqlite-abstract	no
sqljs	no
sqlserver	no

Are you willing to resolve this issue by submitting a Pull Request?

• ✖️ Yes, I have the time, and I know how to start.
• ✖️ Yes, I have the time, but I don't know how to start. I would need guidance.
• ✖️ No, I don’t have the time, but I can support (using donations) development.
• ✅ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.