Changes (partial https://github.com/paritytech/polkadot-sdk/issues/994):
- Set log to `0.4.20` everywhere
- Lift `log` to the workspace

Starting with a simpler one after seeing
https://github.com/paritytech/polkadot-sdk/pull/2065 from @jsdw

.
This sets the `default-features` to `false` in the root and then
overwrites that in each create to its original value. This is necessary
since otherwise the `default` features are additive and its impossible
to disable them in the crate again once they are enabled in the
workspace.

I am using a tool to do this, so its mostly a test to see that it works
as expected.

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>