fix(utils): use plugin to add entries for webpack@5

[ylemkimon]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

Yes, added module federation test cherry-picked from #2723.

Motivation / Use-Case

Fixes #2484 and fixes #2692. Closes #2723.

Instead of modifying compiler configuration and calling hooks.entryOption after it has instantiated, this calls compilation.addEntry to add dev server entries into globalEntry, as suggested in #2692 (comment).

As discussed in #2723 (review), the issue is with reusing the compiler instance with multiple dev servers, so I've decided to use a plugin, whose entries can be modified later.

I've considered using existing plugins:

• EntryPlugin: adds a single entry, so changing the number of entries is not possible because removing hooks is not supported
• DynamicEntryPlugin: adding a global entry, i.e., name: undefined, is not possible because name should be a string (https://git.io/JkleI)

So I've created DevServerEntryPlugin based on DynamicEntryPlugin. It would also allow easy detection.

Breaking Changes

The signature of webpack-dev-server/lib/utils/addEntries has changed from addEntries(config, options, server) to addEntries(compiler, options, server), but GitHub code search shows no code is using this directly.

Additional Info

The first three commits are revert or refactor. Diff ignoring whitespace changes would be better for reviewing changes.

[codecov]

Codecov Report

Merging #2839 (d5089ec) into v4 (6f5d0b6) will increase coverage by 0.03%.
The diff coverage is 97.05%.

@@            Coverage Diff             @@
##               v4    #2839      +/-   ##
==========================================
+ Coverage   93.04%   93.08%   +0.03%     
==========================================
  Files          39       40       +1     
  Lines        1309     1331      +22     
  Branches      349      354       +5     
==========================================
+ Hits         1218     1239      +21     
- Misses         87       88       +1     
  Partials        4        4              

Impacted Files	Coverage Δ
lib/utils/DevServerEntryPlugin.js	94.11% <94.11%> (ø)
lib/utils/addEntries.js	100.00% <100.00%> (ø)
lib/utils/updateCompiler.js	100.00% <100.00%> (ø)

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[alexander-akait]

It is very great idea

[alexander-akait]

Some tests are still flaky 😞

[alexander-akait]

Big thanks

[alexander-akait]

@ylemkimon Now we need focus on target: #2761, then on CLI (drop old code and get code from webpack, when you run webpack-dev-server we should run webpack-cli, now we throw an error) + docs (webpack serve) and I think we will do release

[ylemkimon]

@evilebottnawi Thank you for the review!