[Spec] Should check body _source_ on redirect

[tinovyatkin]

What is the purpose of this pull request?

• Bug fix

While working on #210 I went into a particular interpretation of fetch redirect step 9.

fetch standard:

If actualResponse’s status is not 303, request’s body is non-null, and request’s body’s source is null, then return a network error.

However, our source instead of body source is checking created Request.body. This PR fixes that fact.
This is also important due to fact that we may (want) convert the body to a stream internally, so, we actually must check body source here.

In addition, well-outdated test dependency resumer@0.0.0 was replaced with native Readable.from.

In addition, while doing the above replacement, the hacky test for Buffer.concat failure was replaced with the correct implementation of the stream that can't be concatenated into a buffer.

This PR also bumps Node.JS minimum version to 10.17 from 10.16 (will also be required for #603 and for #210).

[xxczaki]

@node-fetch/reviewers Could you please take a look at this PR?

[larson-carter]

I just have a few questions as to why we are bumping up the dependencies?

[Richienb]

@tinovyatkin @larson-carter wants to know why the minimum version of Node.js is being increased.

[JefferyHus]

@tinovyatkin @larson-carter wants to know why the minimum version of Node.js is being increased.

He already answered this question.

To allow use of Readable.from. It will be also required for the new version of fetch-blob and #603 and #210.