Implement attachment support in Apprise API calls

[dougmaitelli]

💡 The Idea
The scenario:

• I have an Apprise container configured with a multiple notification endpoints
• I have multiple services consuming that container using the Apprise API apprise://...?tags=example
• I should be able to send attachments using these Apprise API calls

I see that some notifications support attachments on Apprise, but these don't seem to work when using the API calls instead of the command line from other services that support Apprise.

[caronc]

Just noticing that this is a duplicate of this.

I did push one change already that starts this process off: #873

[caronc]

Attachment support is complete and merged as part of the latest Apprise API and is only compatible with the latest version of Apprise (v1.4.0) just released today as well.

[dougmaitelli]

@caronc Just a quick question, I guess this now depends on Home Assistant to upgrade their Apprise version right?

[caronc]

The owners of HA are amazingly fast adapting updates. You'll likely see this there in a day or 2.