SecureSocket should use different certificate stores on different isolates

[nex3]

According to sgjesse's comment on issue #8227, SecureSocket shares a certificate store across all isolates. This violates the principle of isolation between isolates, as well as making issue #8227 unfixable. Each isolate should have its own certificate store that's independent of that in other isolates.

[sgjesse]

Marked this as blocking #8227.

[sgjesse]

Currently NSS does not support initialization more that once, and the database is process wide. There might be some work on changing this, see https://wiki.mozilla.org/NSS_Library_Init.

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Added this to the Later milestone.
Removed Priority-Unassigned label.
Added Priority-Low, Waiting labels.

[kevmoo]

Removed Area-IO label.
Added Library-IO, Area-Library labels.

[kasperl]

Removed this from the Later milestone.
Added Oldschool-Milestone-Later label.

[kasperl]

Removed Oldschool-Milestone-Later label.

[sgjesse]

We are currently working on moving from using NSS to using BoringSSL, which have more options for handling different certificate collections.

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cc @whesse.
Removed Type-Defect label.
Added Type-Enhancement label.

[whesse]

The switch to BoringSSL has happened, and all certificates are set on a SecurityContext, which is local to a single isolate. This is in version 1.13, which is currenly on the dev channel, and will be on the stable channel in a couple of months.