Prevent send to token warning

[estebanmino]

Following #6051

This PR adds this validation as a warning instead of an error. With this the user will see Known contract address. as an error but is still possible to send the transaction.

This PR also adds a new object to the send state, called warnings. For now rendered with the component SendRowWarningMessage as the errors, but the idea of this is to easily modify the way we want to show warnings to users, without blocking the transaction validation.

[metamaskbot]

Builds ready [6017b16]: mascara, chrome, firefox, edge, opera

[danjm]

Code changes look good to me!

@estebanmino could you add a screen shot or gif showing what the warning looks like?

[estebanmino]

Sure there is a GIF

As you can see, sending HACK to the address HACK (or any token added manually) or any contract in contract-metadata it will show a Known contract address. message that is part of the warnings added to this PR so the user will still be able to send the token to the address. And this warning will appear only when sending tokens.

If we want to change the color or anything else in that message we just need to modify SendRowWarningMessage, right now working with the same style as errors.

@danjm let me know if we want to change the color of the message or something else.

cc @bdresser @danfinlay

[danjm]

@estebanmino Yeah, let's change the color to orange, as it is just a warning. For example, see the different warning colours we have in the speed up sidebar.

Otherwise this looks good to merge.

[estebanmino]

@danjm changed

[metamaskbot]

Builds ready [b66bbed]: mascara, chrome, firefox, edge, opera

[whymarrh]

LGTM