Add ability to remove message file attachments

[janorivera]

Description

NAMI requested this and they shared the line we needed to add so I took a stab a it.
The attachment button is there by default to in order to make the ff to remain as an "enable" I had to do the if(!feature_flag)

Checklist

• Corresponding issue has been opened
• New tests added
• Feature flags added
• Strings are localized
• Tested for chat contacts
• Tested for call contacts

Other Related Issues

None

Verification steps

AFTER YOU MERGE

1. Cut a release tag using the Github workflow. Wait for it to complete and notify in the #aselo-deploys Slack channel.
2. Comment on the ticket with the release tag version AND any additional instructions required to configure an environment to test the changes.
3. Only then move the ticket into the QA column in JIRA

You are responsible for ensuring the above steps are completed. If you move a ticket into QA without advising what version to test, the QA team will assume the latest tag has the changes. If it does not, the following confusion is on you! :-P

[stephenhand]

LGTM. One minor nit, could you update the config property name to something that makes it clear the flag controls file attaching in flex rather for service users. Like allowOutgoingAttachments or allowFlexToSendAttachments

Or you might consider making the flag negative. preventSendingAttachmentsFromFlex. This has 2 benefits. One, it indicates more clearly this is a standard flex feature we are turning off, rather than one of our features we are turning on. Two, it means that current behaviour will be preserved with no config being applied to a helpline. If I understand correctly, as it currently stands we would have to apply configuration to every helpline before deploying this code to prevent attachments being disabled for them

[gpaoloni]

🚀

(agree with Steve's comment on the naming)

[janorivera]

thanks guys! I made the updates so I'll merge it now