ts: make Provider an interface and update provider functions

[paul-schaaf]

Submodule PRs:

• use new AnchorProvider class and Provider interface armaniferrante/auction-house#10
• use new Provider interface project-serum/swap#30
• use new Provider interface and AnchorProvider implementor project-serum/stake#25

[paul-schaaf]

Submodule PRs:

• use new AnchorProvider class and Provider interface armaniferrante/auction-house#10
• use new Provider interface project-serum/swap#30
• use new Provider interface and AnchorProvider implementor project-serum/stake#25

[paul-schaaf]

Turning this into a draft so we dont accidentally merge it. It is ready for review though

[armaniferrante]

We should remove the wallet parameter and force the caller to sign prior to passing in the tx.

[paul-schaaf]

I remember why I did it this way now. simulateTransaction has all this logic to efficiently get the blockhash and that has to be done before the first signature.

[armaniferrante]

Let's make the simulate changes and merge this!