feat(project): add ssai ads for vod

[AntonLantukh]

Description

1. Add support for server side ads. When "adDeliveryMethod" is set to "ssai" and when "adConfig" is set, then we modify manifest URL and return ads injected at the server side.
2. Some refactoring of the sources function.

Steps completed:

According to our definition of done, I have completed the following steps:

• [ ] Acceptance criteria met
• [ ] Unit tests added
• [ ] Docs updated (including config and env variables)
• [ ] Translations added
• [ ] UX tested
• [ ] Browsers / platforms tested
• [ ] Rebased & ready to merge without conflicts
• [ ] Reviewed own code

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 7d1c1c1):

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[AntonLantukh]

@ChristiaanScheermeijer yeah, I think it is a good idea.

[AntonLantukh]

I will create a ticket in the back-log.