Narrate nesting level when navigating between blocks

[gonfunko]

When navigating between blocks at different levels of nesting, the nesting level of the new block should be added to its ARIA label or otherwise read out to indicate its position in the hierarchy. If this is infeasible, this information could be added to the verbose readout of the block instead.

[BenHenning]

@microbit-robert how strongly do you feel this should be included directly in the main label vs. only including in a verbose readout? My understanding was that it wasn't yet obvious that we definitely wanted to include nesting information in the top-level label since previous feedback suggested that was providing too much context.

[microbit-robert]

I think the ideal solution is a beep that increases / decreases in pitch when the nesting level moves in / out that occurs before the readout, but we know that is not going to happen before user testing in January.

If we include nesting information in the top-level label, then it should probably be at the end of the label.

I think with the other changes that are being made with 'begin' and 'end', this could be restricted to the verbose readout. I agree we should be aiming for the least amount of information as possible to provide understanding. This also ensures we're not testing too many changes at once.