feat: create the eth abi decoding

[albertolerda]

No description provided.

[jaromil]

Related to issue #681 we need to see if used is appropriate, perhaps better use stored?

[albertolerda]

It is actually quite different, the keyword "using", in this case, is used like in the statements compose the secret using '', create the ethereum abi encoding of '' using '', create the jws signature using the ecdh signature in '', .... (it is not a verb, just specify a variable)

In the other PR, the keyword use is specific to ethereum and tells how to fill the field data/value of the ethereum transaction object

[andrea-dintino]

@jaromil we use the keyword 'using' in 7 statements already (include scenario 'secshare'):

https://gyazo.com/a481c21abcae97030f88a8b5391e7c6f

[jaromil]

ACK! thanks