Enable console in the init context

[mstoykov]

This commit does the bare minimal to enable useage of console init
context. Unfortunetely this means that redirection to file is currently
not supported in init context.

This fixes #951

Message for the release notes:

bugfix: console is now usable inside the init context. Unfortunately this doesn't respect --console-output (#1131) , and will be fixed in the future.

[codecov]

Codecov Report

Merging #982 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #982      +/-   ##
==========================================
+ Coverage   72.12%   72.12%   +<.01%     
==========================================
  Files         131      131              
  Lines        9621     9622       +1     
==========================================
+ Hits         6939     6940       +1     
  Misses       2268     2268              
  Partials      414      414

Impacted Files	Coverage Δ
js/bundle.go	83.45% <100%> (+0.12%)	⬆️

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[codecov-io]

Codecov Report

Merging #982 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #982      +/-   ##
==========================================
+ Coverage   73.28%   73.28%   +<.01%     
==========================================
  Files         141      141              
  Lines       10287    10288       +1     
==========================================
+ Hits         7539     7540       +1     
  Misses       2304     2304              
  Partials      444      444

Impacted Files	Coverage Δ
js/bundle.go	82.67% <100%> (+0.13%)	⬆️

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[na--]

As I mentioned in #951 (comment), it'd be fine with merging this as it is for now, despite the known incompatibility with --console-output. But before merging it, we should create a new issue that describes this bug, linking to this PR and the original issue. And we should mention it in a Known bugs section in the release notes, so add that to the PR description please.