UI: Improve look of adv audio control dialog

cmake: Install 'libobs.pc' under the correct 'libdir'

UI: Add Restream integration: stream info widget, channels widget

frontend-tools: Add option to pause output timer when rec is paused

UI: Simplify resize output code

rtmp-services: Add Stripchat streaming service

UI: Declare missing overrides

Allows the users to find their stream key via a specified link if they
opt to just use a stream key instead of integration.

Allows testing bandwidth via streaming without the stream activating
remotely for viewers.

UI, obs-plugins: Add spinbox suffixes where necessary

cmake: Fix typo

libobs: Improve timing of unbuffered deinterlacing

UI: Display infinity symbol when volume is at 0 percent

obs-qsv: Fix QSV reverted features 

The jansson json_ macros already include a null check.

There are devices like the GV-USB2 that produce frames with smmoth
timestamps at an uneven pace, which causes OBS to stutter because the
unbuffered path is designed to aggressively operate on the latest frame.

We can make the unbuffered path work by making two adjustments:

- Don't discard the current frame until it has elapsed.
- Don't skip frames in the queue until they have elapsed.

The buffered path still has problems with deinterlacing GV-USB2 output,
but the unbuffered path is better anyway.

Testing:

GV-USB2, Unbuffered: Stuttering is gone!
GV-USB2, Buffered: No regression (still broken).
SC-512N1-L/DVI, Unbuffered: No regression (still works).
SC-512N1-L/DVI, Buffered: No regression (still works).

libobs: UI: Remove DrawBackdrop() to save fullscreen pass

libobs: obs-filters: Area upscale shader

libobs-opengl: Fix glGetError() infinite loop

Fix audio buffering for devices like GV-USB2

Changing QSV H.264 default profile from "main" to "high"

AsyncDepth = 1 does not mean low latency so we can use default
MaxDecFrameBuffering

It's a waste of GPU time to do two fullscreen passes to render final mix
previews. Use blend states to simulate the black background of
DrawBackdrop() for the following situations:

- Main preview window (Studio Mode off)
- Studio Mode: Program

This does not effect:

- Studio Mode: Preview (still uses DrawBackdrop)
- Fullscreen Projector (uses GPU clear to black)
- Windowed Projector (uses GPU clear to black)

intel GPA, SetStablePowerState, Intel HD Graphics 530, 1920x1080

Before:
DrawBackdrop: ~529 us
main texture: ~367 us (Cheaper than drawing a black quad?)

After:
[DrawBackdrop optimized away]
main texture: ~383 us

As the names entered into this dialog can be used as part of file names
(for example, saving a scene collection), allowing long names can result
in silent data loss where OBS creates the collection and allows the user
to manipulate it, but it cannot be saved on exit. This is due to the
MAX_PATH limitation on Windows (260 characters). 170 was chosen to
accomodate the length of the user app data folder plus some room for
extensions like .json.tmp.

Add a separate shader for area upscaling to take advantage of bilinear
filtering. Iterating over texels is unnecessary in the upscale case
because a target pixel can only overlap 1 or 2 texels in X and Y
directions. When only overlapping one texel, adjust UVs to sample texel
center to avoid filtering.

Also add "base_dimension" uniform to avoid unnecessary division.

Intel HD Graphics 530, 644x478 -> 1323x1080: ~836 us -> ~232 us