[v2.0.0] Change writeBundle signature to match generateBundle

[lukastaegert]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:
Resolves #2717

Description

This is one of the few truly breaking changes in this release as there is no two-step deprecation; but to be honest, I could not think of another good name for this hook and well, writing a downward compatible plugin is not that difficult because you can do this:

{
  writeBundle(options, bundle = options) {
    // now bundle is always the bundle, both in 1.x and 2.x
  }
}

So you can detect the signature of the hook by checking if the second parameter is used; in that case, it is the bundle, otherwise the first is the bundle.

[codecov]

Codecov Report

Merging #3361 into release-2.0.0 will not change coverage.
The diff coverage is 100%.

@@              Coverage Diff               @@
##           release-2.0.0    #3361   +/-   ##
==============================================
  Coverage          94.07%   94.07%           
==============================================
  Files                174      174           
  Lines               5977     5977           
  Branches            1768     1768           
==============================================
  Hits                5623     5623           
  Misses               191      191           
  Partials             163      163

Impacted Files	Coverage Δ
src/rollup/rollup.ts	100% <100%> (ø)	⬆️

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[bathos]

This would absolutely be useful to us! Currently we obtain output options in generate bundle in one plugin but act on them in writeBundle — which works because in this case there’s only one output, but I suspect it would imply a race condition if we did have more than one output.