chore: add support for npm8

[villebro]

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Since npm@8 is nowadays the default on Node LTS (16 at the time of writing), we should add support for it to get rid of this warning (both locally and on CI) when building frontend assets. Here I've arbitrarily chosen ^8.1.2 as that's what I currently have, but 7.x || 8.x would probably work equally well.

BEFORE

Currently this warning is displayed when building with npm@8

AFTER

With this PR the warning no longer appears:

TESTING INSTRUCTIONS

CI

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[kgabryje]

LGTM

[codecov]

Codecov Report

Merging #19365 (8e8a0fa) into master (45c28c8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #19365   +/-   ##
=======================================
  Coverage   66.67%   66.67%           
=======================================
  Files        1676     1676           
  Lines       64714    64714           
  Branches     6506     6506           
=======================================
  Hits        43150    43150           
  Misses      19878    19878           
  Partials     1686     1686           

Flag	Coverage Δ
javascript	51.32% <ø> (ø)

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