oradb_manage_db: support for dbca custom scripts

[talek]

It should be possible to deploy all custom scripts defined in a dbca template. With this PR you may define the following section in your dbca template:

<CustomScripts Execute="true"><CustomScript script="{ORACLE_HOME}/assistants/dbca/templates/{{ dbh.oracle_db_name }}_post_install_script.sql"/></CustomScripts>

Then, customscripts variable for the database to be created should point out to the relevant custom scripts defined in the template:

oracle_databases:
  - home: 19c
    oracle_db_name: DUMMYDB
    dbca_templatepath: templates/
    dbca_templatename: dummydb.dbt
    ...
    customscripts:
      - post_install_script.sql
    state: present

All defined custom scripts are copied over to the target remote ORACLE_HOME/assistants/dbca/templates/, from the same dbca_templatepath location. Like the dbca template file, the scripts are staged on the target, prefixed with the name of the database.

[Rendanic]

It took a moment until I understand how this is working.
Great solution - I like it and thanks for the enhancement.