Fixes rounding issue when creating colour filter queryVector
Adds test combining query and knn colour search
not sure it's in the right place
please check whether the expected results for combines free test query and knn search in search/src/test/scala/weco/api/search/images/ImagesFiltersTest.scala is what we actually want:
blue foot and pretty blue foot come first,
3rd is the red foot because it's a closer match for foot even though it's not blue
4th in line is less foot but more blue, and come after the red foot because foot takes precedence
5th is no foot but it's blue
6th is not foot nor blue
combines free test query and knn searchinsearch/src/test/scala/weco/api/search/images/ImagesFiltersTest.scalais what we actually want: blue foot and pretty blue foot come first, 3rd is the red foot because it's a closer match for foot even though it's not blue 4th in line is less foot but more blue, and come after the red foot because foot takes precedence 5th is no foot but it's blue 6th is not foot nor blue