feat: add evm_unlockUnknownAccount

[davidmurdoch]

Accidentally permanently closed the previous PR. Reopening here.

This feature is much-needed for on the fly transaction creation, I hope you accept this PR! I can write more tests if required

@aaryamannchallani

[davidmurdoch]

@aaryamannchallani I pushed my local develop branch, instead of the PR branch, to your PR, which resulted in the PR being permanently closed. Sorry about that. I've pushed the correct branch up here and reopened the PR. I'll continue the Code review here.

[davidmurdoch]

@aaryamannchallani Nevermind! It seems I cannot give you write-access to just this branch, so I'll make the necessary changes myself.

will it be in the next version slightly_smiling_face

Yes, I'm planning on shipping this in the next beta release.

[coveralls]

Coverage increased (+44.1%) to 82.697% when pulling f9476ab on aaryamannchallani-develop into a581d91 on develop.