Remove the beta release folder and replace with a symlink to the
'latest' release.
Including beta firmware in the APT release causes unecessary churn
and occasionally causes an issue where a user might end up on an
old and unsupported beta release.
Instead, beta releases are will be feature specific and installed
manually via 'rpi-eeprom-config --edit beta-firmware.bin'
i.e. beta releases will be out-of-package custom firmware releases
downloaded from github. The functionality will be merged into
a new latest/stable release or abandoned.
N.B. The old beta releases have been archived to 'old' but are no
longer included in APT.
Move these out of the directories selected by APT now that 2020-09-03
is the default release.
Preserve the releases which were promoted to stable in-case these are
referenced via scripts.
Now that 2020-04-16 has been released and appears to be stable move
the older binaries to and old (deprecated) directory. There's no
need to include old beta binaries in OS packages.
