Give the user the ability to opt out of 3rd party network validation when adding a new network

[pedronfigueiredo]

Explanation

This PR gives the user control over the privacy settings for enabling or disabling a call to https://chainid.network/chains.json.

This is achieved by adding the toggle to the preferences controller and the condition in the appropriate place.

Integration tests are included.

• Fixes #876

Screenshots/Screencaps

[insert screenshot from test]

Manual Testing Steps

• Go to the privacy settings screen
• Disable validation
• Validate (in the network tab on dev tools) that the request is not made.

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [779a6cd]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5, 6
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1043 ± 371 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	87	153	103	15	7
		domContentLoaded	69	122	94	13	6
		load	80	1828	1043	773	371
		domInteractive	69	122	94	13	6

Bundle size diffs [🚨 Warning! Bundle size has increased!]

• background: 224 Bytes (0.01%)
• ui: 2.08 KiB (0.03%)
• common: 610 Bytes (0.01%)