Slack: Mark edited messages with a pencil icon

[nylen]

When sending messages to Slack, edited messages are updated silently without the (edited) text that appears when a regular user edits a message.

We can't fix that, but we can make a cosmetic improvement to make it clearer that the message was edited:

In (Discord)	Out (Slack)

[patcon]

Related: #614

[42wim]

The pencil icon idea is pretty cool.
There already is an EditSuffix option which allows you to set a "(edited)" message of your choice. (you could set it there)

matterbridge/matterbridge.toml.sample

Lines 414 to 416 in f88c5f6

	#Message to be appended to every edited message
	#OPTIONAL (default empty)
	EditSuffix=" (edited)"

I think it's better to add a EditPrefix option if you/other people really need it prefixed.

[nylen]

Same as in #682...

There already is an EditSuffix option which allows you to set a "(edited)" message of your choice. (you could set it there)

I didn't see this, maybe it's in a different part of the code. I think this will work fine...

I think it's better to add a EditPrefix option if you/other people really need it prefixed.

No strong feelings about this. Probably not worth adding another setting, especially if the suffix already works.

I'll test the suffix and either fix it in this PR, or close this PR.

[nylen]

Closing, I haven't had time to revisit this, and as discussed above it may already be covered by existing functionality.