improve v2-plot support in plot-sync

[arvidn]

Purpose:

Add support for v2 plots to the Plot class. This is part of the plot sync protocol and the harvester protocol. In order to support v2 plots, we need a strength field, but we also need to stay backwards compatible with previous versions of harvesters. e.g. DrPlotter.

In order to do so, the size field is reused to now either have the v1 plot size or the v2 plot strength. The most significant bit in the uint8 field determines which one it is.

The field was renamed from size to param to match the naming of similar fields in other parts of the code.

Current Behavior:

the plot sync protocol does not support v2 plots.

New Behavior:

the plot sync protocol supports v2 plots

[arvidn]

maybe the harvester protocol version number should be bumped

[github-actions]

File	Coverage	Missing Lines
chia/harvester/harvester.py	50.0%	lines 200-201
chia/plot_sync/sender.py	66.7%	lines 45-46
chia/protocols/harvester_protocol.py	80.0%	lines 161

Total	Missing	Coverage
22 lines	5 lines	77%

[arvidn]

the missing test coverage is because we don't have any v2 plots in CI yet. This will be addressed

[wjblanke]

aok