348: Add aribitrary texture size handling to the capture example r=me a=rukai
* User can specify width + height via arguments.
* Defaults to (100, 200) when no arguments. Odd values chosen to make it more likely to pick up issues when testing.
* Converts from bgra as I believe that is the most commonly supported format for swapchains?
Co-authored-by: Rukai <rubickent@gmail.com>