Remove onNewRenderLine

[jtpio]

Fixes #159.

Not exactly sure why we had this in the first place. But the onNewRenderLine was modifying the breakpoints model directly and triggering CodeMirror issues (#159).

Instead we'll want to send the dumpCell and setBreakpoints requests via the service when a user modifies the content of a cell.

[jtpio]

cc @KsavinN if you want to have a look

[KsavinN]

There is good news and bad:

Realy great is that fix #159

but its seems we need found solutions for this:
example in vs-code:

and now in this PR:

[jtpio]

Yes that's right.

But since we need to sync the content of the cell when it is modified on the frontend, we'll also have to update the breakpoints. The flow would be something like this:

• Add a signal connection to activeCell.model.contentChanged.
• When a user changes the content of the cell, the signal will be emitted.
• Send dumpCell and setBreakpoints, probably behind an ActivityMonitor or Debouncer to avoid sending to many requests.
• Since the service is responsible for updating the breakpoints, the view will refresh itself when a response has been received from the kernel and the model changed.

[jtpio]

Opened #162 so we can track that in a separate issue.