[MM-36015] Updates npm packages

[jfrerich]

Summary

This PR updates npm packages to resolve vulnerabilities

Based off of branch compare

Initial npm audit results:

• found 233 vulnerabilities (2 low, 14 moderate, 217 high) in 919 scanned packages
  • run npm audit fix to fix 222 of them.
  • 8 vulnerabilities require semver-major dependency updates.
  • 3 vulnerabilities require manual review. See the full report for details.

npm audit fix response

• fixed 222 of 233 vulnerabilities in 919 scanned packages
  • 3 vulnerabilities required manual review and could not be updated
  • 3 package updates for 8 vulnerabilities involved breaking changes
  • (use npm audit fix --force to install breaking changes; or refer to npm audit for steps to fix these manually)

rerun npm audit response after npm audit fix

• found 9 vulnerabilities (2 low, 6 moderate, 1 high) in 920 scanned packages
  • 8 vulnerabilities require semver-major dependency updates.
  • 1 vulnerability requires manual review. See the full report for details.

Run suggested commands from npm audit response

• npm install --save-dev webpack-cli@4.7.0
• npm install react-markdown@6.0.2

Ticket Link

https://mattermost.atlassian.net/browse/MM-36015

[hanzei]

@DHaussermann Let's test this PR in release testing