Support underscore '_' character for snake_case in Aspire PostgreSQL database names

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

You cannot create a Postgres database name with an underscore character in the name like 'my_database' which is also very normal for Postgres users to name databases with snake_case. Hyphen is allowed example 'my-database'.

### Describe the solution you'd like

Add underscore '_' to the allowed characters for Aspire Postgres database names: Example 'my_database'.

### Additional context

Compiler Error ASPIRE006