Implement associated MIME info for fake plugins

[pilgrim-brave]

Resolves brave/brave-browser#10718

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)
• 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:

As per brave/brave-browser#10716, run through the following STR/Cases:

1. Go to espn.com
2. Scroll to any of the videos.
3. Hit play button on any of the videos (the short ones not the ones that to go to premium service) and notice the video doesn't play.

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.

[pilgrim-brave]

all test failures are known and unrelated

[kjozwiak]

Verification PASSED on macOS 10.15.6 x64 using the following build:

Brave | 1.13.45 Chromium: 84.0.4147.89 (Official Build) nightly (64-bit)
-- | --
Revision | 19abfe7bcba9318a0b2a6bc6634a67fc834aa592-refs/branch-heads/4147@{#852}
OS | macOS Version 10.15.6 (Build 19G73)

• Verified the STR/Case outlined via [Desktop] espn.com videos don't play with standard fingerprinting blocking (default) brave-browser#10716
• ensured that videos play without any issues on https://www.espn.com
  • ensured it worked in Normal, PB, Guest and Tor windows

[rebron]

Reproduced original issue on macOS 1.12.98 and Windows version below.

Brave	1.12.91 Chromium: 84.0.4147.89 (Official Build) beta (64-bit)
Revision	19abfe7bcba9318a0b2a6bc6634a67fc834aa592-refs/branch-heads/4147@{#852}
OS	Windows 10 OS Version 2004 (Build 19041.388)

Verified PASSED on macOS 1.13.45 and Windows below:

Brave	1.13.42 Chromium: 84.0.4147.89 (Official Build) nightly (64-bit)
Revision	19abfe7bcba9318a0b2a6bc6634a67fc834aa592-refs/branch-heads/4147@{#852}
OS	Windows 10 OS Version 2004 (Build 19041.388)

Using STR via brave/brave-browser#10716