Include chainspec, config and accounts TOML resources when publishing the Execution Engine testing test support crate.

[SaiProServ]

Genesis requests exported by the testing crate require the presence of a sample chainspec. We need to include this chainspec when publishing the test support crate.

[jacek-casper]

We've identified the issue to be the fact that the local chainspec is a symlink which points to a gitignored file which is generated during the node build with make. The file is not present when the test-support crate is built as a cargo dependency alone. We intend to fix it by packaging chainspec.toml.in with the test support crate and adding a small step in its build script that will generate the local chainspec automatically during a cargo build.

@deuszex @alsrdn