Bug fix: Remove incorrect typings from contract

[eggplantzzz]

In response to #4825, this PR removes the types from @truffle/contract.

[haltman-at]

We said we're doing this, right? So let's do it! (Although, should this be marked as a breaking change to contract?)

[eggplantzzz]

@haltman-at oh man, I don't know. I guess they never worked so maybe not?

[cds-amal]

Outta here!

[wbt]

Yep...this was a breaking change on @truffle/contract put out on a patch-level bump. I'd really hoped this cluster of projects would get away from that practice, but it's unfortunately still fairly common.

Prior to merging this, there was a way to get Typescript to compile a TypeScript file with the line "import TruffleContract from '@truffle/contract';" (though it would drop that import in the transpiled code) and now previously working code can't even get past that line in failing to compile:

error TS7016: Could not find a declaration file for module '@truffle/contract'. '/project/path/node_modules/@truffle/contract/index.js' implicitly has an 'any' type. Try npm i --save-dev @types/truffle__contract if it exists or add a new declaration (.d.ts) file containing declare module '@truffle/contract';