Autoloader: Added support for aliases

[RunDevelopment]

This PR adds alias support to the Autoloader plugin.

The bug that the dependencies of forced-loaded languages in data-dependencies were not loaded is also fixed.
I.e. <code class="language-pug" data-dependencies="less!"> the dependencies of less were not loaded.

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This resolves #1827.

[falsandtru]

Can you expose lang_aliases to enable custom aliases?

[RunDevelopment]

Before thinking about custom aliases, are 'normal' aliases not enough?
For what purpose do you need them?

[falsandtru]

I want to define the hs alias for haskell. Looks like I have to register that alias to lang_aliases.

[RunDevelopment]

hs is the file extension of Haskell files, right? Then making hs an alias for haskell is an easy solution to your problem.
Also, there are others who might also want this alias, so making this part of Prism is probably a better idea than introducing custom aliases.

If there are any other aliases you want, feel free to request them, I'll add them.

If you want to add them yourself:

1. Add a line Prism.language.myNewAlias = Prism.languages.mylanguage; to the prism-mylanguage.js file in the components/ directory.
2. Open components.json and add an alias property to the entry languages.mylanguage and set its value to the added alias. E.g. "alias": "myNewAlias " or "alias": ["firstAlias", "myNewAlias "].
3. Run the npx gulp command after installing all npm dependencies.
4. Commit and make a PR (without package-lock.json)!

[falsandtru]

I see, could you add hs alias with #1830? Since hs alias is adopted with GitHub it can be considered a common alias.

[RunDevelopment]

I'll make a new PR (#1831).

[falsandtru]

Thanks!

[mAAdhaTTah]

We'll also want to update the gulp annotations PR, which may be worth revisiting now.

[RunDevelopment]

I closed #1535 because I want to get rid of partly generate files in the end.
My goal is to implement #1539 (or similar) so that we generate files that these plugins then require. This will also get rid of the annoying merge conflicts I get almost every time in prism-autoloader.js and prism-show-language.js.