Need to add tests for the sending process

[DenBond7]

Need to add tests for the following (that a message will be sent)

• a regular message
• a regular message + att
• a regular message + forwarded att
• an encrypted message
• an encrypted message + an encrypted att
• an encrypted message + an encrypted forwarded att

Originally posted by @DenBond7 in #1630 (comment)

[DenBond7]

Before starting need to drop all JobIntentService implementations and use WorkManager instead.

Edit: found a way to do complete the current issue without it.