Refactor UpdateDisplay() to call UpdateUploadRate()

[ann0see]

Short description of changes

Refactor UpdateDispay() method. This was extracted from https://github.com/jamulussoftware/jamulus/pull/2550 and is related to: https://github.com/jamulussoftware/jamulus/pull/3364/files/21815c1a0708979fe0414c30e0294feaa7632be3#r1759185427

It makes sense to call UpdateUploadRate() from UpdateDisplay() since it gets same functionality to the same place.

Not sure, if the condition is correct, as we do not check if pClient is running, but rather it is connected now.

CHANGELOG: SKIP

Context: Fixes an issue?

No.

Does this change need documentation? What needs to be documented and how?

No. This even adds documentation

Status of this Pull Request

Ready for review

What is missing until this pull request can be merged?

Review. Tested locally by disconnecting and connecting via GUI and changing Audio quality and enabling/disabling small network buffers. Network rate shows correctly. Also checked by starting Jamulus with -c flag and seems to do what it should do: Label shows correct data if connected and --- if not connected.

Checklist

• [x] I've verified that this Pull Request follows the general code principles
• [x] I tested my code and it does what I want
• [x] My code follows the style guide
• [x] I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• [x] I've filled all the content above

[pljones]

Currently we show the rate only on the settings page.

The factor that connecting to a server affects in the calculation is the "Small Buffers" overhead, I think. I can't think of anything else that would need to check for server support before performing the calculation.

Originally - before "Small Buffers" - I think it was calculated just from the audio settings, as the network overheads were fixed.

So I guess this change makes sense and is, therefore, long overdue.

[ann0see]

@softins could you please have a look at this?