Implement Bluebird.method(fn)

[v1rtl]

Ref: https://github.com/petkaantonov/bluebird/blob/3817d50b9d6aa6ca949073939f428925bd8aae2d/src/method.js#L12-L22

[Lionad-Morotar]

How about this implementation? Umm, I feel like it hasn't been thoroughly tested, even though it passed all the Bluebird.method test cases.

main...feat-method

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