Configure various dev tools

[Steffo99]

This pull request pre-configures various dev tools to allow an easier onboarding for potential new developers.

In particular:

• The .vscode and .idea directories are unexcluded, as they're not supposed to be excluded in first place

  • The .idea directory is left to be managed by IDE itself via the .idea/.gitignore file in it

• The .vscode directory is pre-populated with settings to aid development in VSCode:

  • A run configuration to launch Phanpy on port 8080 and to open an instance of a Chromium-based browser in debug mode on it as soon as the server is done launching:
    

  • A recommendation for the github.vscode-github-actions extension that adds features to work on GitHub Actions files, such as proper syntax highlighting:

  • If the user has File Nesting enabled (it is not by default), its settings are extended to group together *.tsx, *.jsx, *.ts, *.js, *.module.css and *.css files with the same name:
    

  • The src/locales and node_modules directories are hidden by default from the file explorer and excluded from search, as they're not meant to be edited by hand

• The .devcontainer directory is created with a basic but functional configuration to develop Phanpy in a development container, such as the ones provided by GitHub Codespaces

• The .idea directory is pre-populated too with settings to aid development in Jetbrains' IDEs:

  • Project name has been set to "Phanpy" instead of whatever the current working directory is called

  • Code style settings are setup to be overridden by the project, which copies the Prettier features built-in in the IDE

    • Further code linting can be later performed before-commit by the external Prettier plugin

  • Basic module structure

  • A «Scope» is setup to mark localization files managed by Crowdin with a red colour, denoting that they should not be edited

• The port for the development server has been changed from 5173 to 8080; while both are well-known for Vite development, only the latter is officially registered with the IANA for web development

• Metadata is added to package.json to prevent accidental publishing ("private": true) and to have additional information if needed

• The prettier-pr.yml GitHub Action is extended to allow it to automatically prettify files, instead of just checking them

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Since this is a lot of opinionated stuff, if you're not comfortable with merging parts of it, I'd recommend you to cherry-pick the commits you think might be interesting, or to tell me which parts you like so that I can cherry-pick for you!

[cheeaun]

1. Personally not a fan of editor-specific configs. There are too many editors out there (in the past, in the present, and will be many more in the future) with too many configs 🙈
2. Prettier action is nice, tho' now I would prefer it to show warnings first (thus blocking the PR merge) instead of auto-fixing them — good for telling future contributors that they need this set up on their editors instead of relying on CI to auto-fix for them.
3. Not sure if accidental publishing is common, but I don't think that should be our concern here(?) 🤔, re: package.json changes. I'm also not sure if all the metadata would be useful in other context as I prefer that file to be as minimalistic as possible.