Open channels automatically when onboarding

[AlexD10S]

In the onboarding script add logic to create automatically the HRMP channels between parachains.

This task will involve:

• Modify the Issue Template in order to specify all the parachains you want to open a channel with.
• Modify the github actions to read this parachain_ids and pass as a parameters to the CLI Script
• Update the script code to execute the calls to open HRMP channels with these parachain ids.

[al3mart]

Created #594 to address the first bit