feat(topology/path_connected): add lemmas about paths and continuous …

…families of paths (#4063)

From the sphere eversion project (see leanprover-community/sphere-eversion#12)



Co-authored-by: Anatole <anatolededecker@gmail.com>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
Co-authored-by: Anatole Dedecker <48656793+ADedecker@users.noreply.github.com>