Breakpoints based on Container width and not window width with ResizeObserver

[katerlouis]

Is your feature request related to a problem? Please describe.
I have a swiper instance with 3 slides. When they all fit inside the container, I want to disable sliding and all controls and just use swiper as a layout. When they don't fit the parent any longer, I want "swiper to be an actual slider with certain swiper settings"

Describe the solution you'd like
containerBreakpoints: {} property that works just as breakpoints: {} does, but using ResizeObserver for width changes and not window.matchMedia() or window.resize()

Describe alternatives you've considered
I guess I could do something similar myself. But I'm too afraid to run into bugs. Swiper is pretty complex and I've run into a lot of issues over the years, when trying fancy stuff with updating settings and killing and re-initializing the instance etc.

[ettoredn]

Does this fix #4019 and #2218 ?

[nolimits4web]

@ettoredn yes, thanks