feat(estatico-boilerplate): extract dependency graph resolvers

[backflip]

Goal: Remove some boilerplate code from gulpfile.js to make it

• more readable
• easier to maintain (fixing something in a resolver can be done in estatico-watch and used in every project without the need to touch gulpfile.js)

[backflip]

@orioltf, @christiansany: What do you think about this (moving the default dependency graph resolvers from the gulpfile into the estatico-watch package)?

[CLAassistant]

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2 out of 3 committers have signed the CLA.

✅ backflip
✅ orioltf
❌ Christian Sany

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