Multiple fixes & improvements related to volume and audio.

[dbuezas]

Fix setting HW Volume from web UI

• The input field had no ID, and the js script ignored that field

Fix setting filter from web UI

• The path to setconf was wrong in ui_camera.cgi

Expose SW volume in web UI

• This is useful for low volume cameras.
• Mine for example has very low sensitivity without SW volume turned up

LIVE Update audio volume and filters, FPS and OSD settings from the Web UI

• Volume updates as soon as you release the mouse while scrolling the slider
• Without interrupting the stream
• It is not persisted unless one clicks save
• Useful for testing filters and volumes before saving

Volumes (HW and SW) exposed via MQTT

• Persisted
• Both scaled to appear as 0 to 100%

[dbuezas]

It works well, the only issue I am having is:

• Something is resetting the HW and SW volumes to 70 and -1 on each restart (it works now)

And the only feature I'd like to add is:

• Expose them via mqtt (done)

[jmtatsch]

Thank you for your contribution.

[dbuezas]

Gladly, I wanted to understand the internals of this and ended up learning lots more about bash.

[jmtatsch]

Haha yes, there is a reason why the repo is called defang hacks 😉