checkDaggerDataWithProof() should be replaced by unmaskWithEthash()

[qizhou]

• checkProof should be done in the contract
• Decode should be done in precompile

[LiuJiazheng]

I made an intial version of it. Please have a check on this:
b3b870c

It merely provides a skeleton while two (obvious) questions remain:

1. Have we finalized Ethash details? I leave a blank in corresponding area. Meanwhile, our current tests are based on "raw data" since before we never adapt an encoded/decoded version;
2. If TestSystemContractDaggerHashimoto could be shifted in this shape, how does our precompile test could be? Or in a more concrete fashion, what, to be tested for a precompile simmulation?

[qizhou]

Great! I will let @cyl19970726 follow up on this and see if we need more tests.

[qzhodl]

some comments here: b3b870c#r106689902

[LiuJiazheng]

Yanlong is working on this based on my previous skeleton