[sailfish-browser] Rebase text selection feature to latest master

This PR depends on https://github.com/tmeshkova/embedlite-components/pull/53

Comparing to the previous PR (https://github.com/sailfishos/sailfish-browser/pull/78) here
1. selection handles are positioned vertically centred to text lines;
2. the handles are concentric circles;
3. WebContainer got one new member decoratorColor.