Video headers have a mix of code styles

In Video headers there seem to be weird mix of code styles. There are camel cases, snake cases, different capitalization, hungary notation or not, bracket whitespace, etc:

```
uint16_t elemental_duration_in_tc_minus1[7];
StdVideoH265SubLayerHrdParameters* SubLayerHrdParametersNal[7];
StdVideoH265DecPicBufMgr* pDecPicBufMgr;
uint8_t refList0ModOpCount;

typedef struct StdVideoH265PredictorPaletteEntries
{

typedef struct StdVideoH265SpsFlags {
```

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Also it includes using semi-absolute path, e.g. `#include "vk_video/vulkan_video_codec_h264std.h"`, which is making assumptions about the include paths. This is problematic for e.g. people that just copy-paste headers directly into their project.

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The headers having their own versions is kinda weird and unnecessary. Given that Vulkan updates like each 2 weeks on average, it feels they would fit under that release schedule (or be accomodated anyway if there is a change).

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Not sure if the `Std` prefix is useful or just noise. In some C++ bindings it could clash with `std::`.

Some C-namespace is probably warranted though. Any reason this doesn't just borrow `Vk`?