Display & configure memory page map.

As seen at https://www.youtube.com/watch?v=lF7Di5Qwut4&t=2767s it isn't clear how is page map affecting the execution of the code in PVM debugger.

I believe it would be good to:
1. [ ] Display access type of the page in a memory tooltip (readable / writeable / non-accessible). We may even have different background colors indicate page accessibility.
2. [ ] View current page map (it may change during execution because of `sbrk`)
3. [ ] Edit the page map (currently it's only possible to either load JSON file or SPI to have that configured)
4. [ ] Store page map in the URL (to allow easy sharing). The `?program` parameter might even be SPI program.