Update Camera App helper for configurable video captureing tests

The following public functions are added:
- setEIS
- setFrontVideoResolution
- setBackVideoResolution
- setFrameRate

The following private function(s) are added/modified:
- selectVideoResolution
- set4KMode
- findSettingItem

Change-Id: If995bfe755120035a574e2e7ad32ce96929f7ab5