Summary:
`storybook` + `html-webpack-plugin` seem to not play nicely with webpack4. https://github.com/storybookjs/storybook/issues/9216
Force resolving `html-webpack-plugin` to a new alpha version seems to work.

`babel` modules need to be upgraded to address `.mjs` files. https://github.com/babel/babel/issues/8462

`favicons-webpack-plugin` needs to be upgraded to handle API changes for webpack plugins https://github.com/jantimon/favicons-webpack-plugin/issues/222
Upgrading to the new alpha version seems to work.

A handful of other plugins also don't work due to API changes in webpack but upgrading them to their latest stable versions works.

Test Plan:
Build time perf for Webpack4:
```
=== PHASE SUMMARY INFORMATION ===

Total launch phase time         1.200 s    0.59%
Total init phase time           0.342 s    0.17%
Total target pattern evaluation phase time    1.228 s    0.61%
Total interleaved loading-and-analysis phase time    1.807 s    0.89%
Total preparation phase time    0.058 s    0.03%
Total execution phase time    197.507 s   97.70%
Total finish phase time         0.013 s    0.01%
------------------------------------------------
Total run time                202.157 s  100.00%

Critical path (197.212 s):
       Time Percentage   Description
   91.785 s   46.54%   action 'Generating webpack deps src/ui/ui-deps.tar.gz'
   10.071 s    5.11%   action 'Generating licenses src/ui/npm_licenses.json'
    40.3 ms    0.02%   action 'Executing genrule //tools/licenses all_licenses'
   95.316 s   48.33%   action 'Generating webpack bundle src/ui/ui-bundle.tar.gz'
```

Build time perf for Webpack5:
```
=== PHASE SUMMARY INFORMATION ===

Total launch phase time         0.020 s    0.01%
Total init phase time           0.180 s    0.09%
Total target pattern evaluation phase time    0.118 s    0.06%
Total interleaved loading-and-analysis phase time    0.145 s    0.07%
Total preparation phase time    0.007 s    0.00%
Total execution phase time    207.184 s   99.77%
Total finish phase time         0.004 s    0.00%
------------------------------------------------
Total run time                207.660 s  100.00%

Critical path (207.116 s):
       Time Percentage   Description
   93.509 s   45.15%   action 'Generating webpack deps src/ui/ui-deps.tar.gz'
   10.430 s    5.04%   action 'Generating licenses src/ui/npm_licenses.json'
    30.0 ms    0.01%   action 'Executing genrule //tools/licenses all_licenses'
  103.148 s   49.80%   action 'Generating webpack bundle src/ui/ui-bundle.tar.gz'
```

Reviewers: #engineering, michelle, nick

Reviewed By: #engineering, michelle, nick

Subscribers: nick

Differential Revision: https://phab.corp.pixielabs.ai/D6761

GitOrigin-RevId: 6584b9806e6c35138b721af6e522b6da7a60b36b