MemoryViz.js: format, move style (#106482)
This updates the JS format of MemoryViz.js to match internal format.
It also moves the style sheet into the JS so it is easier package for
both oss and internal use.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106482
Approved by: https://github.com/aaronenyeshi
ghstack dependencies: #106328
