Code changes required to add yugabyte support as a dialect

[priyanshi-yb]

This PR includes changes required for adding yugabyte support as a dialect in SequelizeORM.

1. Added separate dialect for the yugabyte under src/dialects and extended the postgres dialect.
2. Modified few files to support the newly added dialect.
3. Modified the test suite for postgres specific cases to work for us as well and skipped the ones failiing with not supported/assertion errors/operation timed out errors.
4. Added the scripts to start and stop docker container via docker-compose.yml for yugabyte under dev directory.