StereoEnhancer code style enhancements

[betalars]

replacing r l with right and left to increase redability.

I probably wouldn't have done this if it wasn't for a similar commit by @AThousandShips I found while blaming a different file ...

[AThousandShips]

By my changes do you mean:

• Fix member names of AudioFrame to match extension #87006

That wasn't about style but about matching the bindings, this is a bit different (I in fact left this file without changing these parts when making that change)

[betalars]

Oh, I missed the bigger picture. Okay you may discad this then, I think it makes code more readable, but I don't have too strong feelings about this.

[AThousandShips]

I think it could be worthwhile but I'd say it's still pretty readable from context, but I don't think it needs to be rejected outright

I would say it belongs as part of a broader sweep of readability improvements, like the ones tracked in:

• [TRACKER] Typos and UI Paper Cuts #91521

Would be good to open a tracker for things like this as well

[fire]

Since there isn't many audio maintainers, you might have to do extra work like provide audio clips or anything for us to test that this isn't a regression.

[betalars]

@fire wrote

Since there isn't many audio maintainers, you might have to do extra work like provide audio clips or anything for us to test that this isn't a regression.

I mean yes, but you can also check the code manually, because I did not touch the logic intentionally, even tho I saw some reasons to.

[adamscott]

That PR is on the line of being not needed per se, but it seems fine. Line by line, nothing seems to have changed.

[akien-mga]

I would say it belongs as part of a broader sweep of readability improvements, like the ones tracked in:

• [TRACKER] Typos and UI Paper Cuts #91521

As suggested here, I merged this changes as part of a bigger commit in #99799, which supersedes this PR.

Thanks for the contribution!