[Juicenet] Fix Charging state controls and override functionality (#15566)

[Juicenet] Fix Charging state controls and override functionality (#15566)

* [Juicenet] Fix typos in setOverride()
 Some obvious typos in setOverride() result in the timestamp being
  ignored which causes it to fail

Fixes #15564

* [Juicenet] Allow disabling the override
 - The charger has default settings upon plugin, changing the current state
    sets the overide to Y, this makes override settable only in the N direction
    to remove whatever settings were previously applied

* [Juicenet] Document new writable status of override

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Signed-off-by: Ed Martin <edman007@edman007.com>