Update Rust compiler to latest stable (1.46.0)

[tmancey]

Resolves brave/brave-browser#11802
Fixes brave/brave-browser#11782

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint, npm run gn_check)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[bsclifton]

Looks like Linux and Android worked - but each ran into an audit_deps problem. Should be good to go! 😄

• https://ci.brave.com/job/pr-brave-browser-issues-11802-android/1/execution/node/138/log/
• https://ci.brave.com/job/pr-brave-browser-issues-11802-linux/1/execution/node/153/log/

[bsclifton]

++ - although let's see if the audit_deps warnings (links above) are a blocker:

For example:

/home/ubuntu/workspace/pr-brave-browser-issues-11802-linux/src/out/Component_audit/../../brave/build/rustup/0.1.5/bin/cargo-audit: /lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.29' not found (required by /home/ubuntu/workspace/pr-brave-browser-issues-11802-linux/src/out/Component_audit/../../brave/build/rustup/0.1.5/bin/cargo-audit)

Is this the same as what is captured in brave/brave-browser#7055?

[bsclifton]

Unless we need this, I think we can close this as cargo-audit 1.12.1 has been published, which pins the version and fixes the error we had seen