Update installation docs to use templates + esbuild instructions

[kevinfiol]

Replaces https://github.com/MithrilJS/mithril.js/pull/2827

Removes wordy "Step by Step" section of the installation page, as well instructions on using budo, and adds Mithril starter templates that are easy to clone. Also rewrites Quick start section to use esbuild instead of Webpack.

Description

• Remove instances of using npm install with the --save flag as that flag is no longer necessary since npm v5.
• Remove Step by step section
• Remove Alternate ways to use Mithril.js section
• Rewrite Quick start with Webpack to use esbuild instead.

• Add "Create a project locally" section that lists three different templates a user can get started with:

  • mithril-esbuild-starter
  • mithril-vite-starter
  • mithril-rollup-starter

Review the rendered markdown here.

Motivation and Context

• Why is this change required? What problem does it solve?
  • Simplifies installation documentation
  • Moves the documentation to use newer, more up-to-date and performant tools. Webpack has a much larger dependency graph while being far less performant than esbuild, rollup, or Vite.

For some notes on why I went with esbuild as the "default":

• Usage is dead simple since it's primary usage is through the CLI; no config needed to write an npm script
• It's a small-ish static binary and is well suited for single-page applications, which Mithril embraces
• Appeals to minimalists and folks unfamiliar with JS ecosystem. See this post
• It will arguably be around longer than Vite (fwiw, Vite sits on top of esbuild)

How Has This Been Tested?

Ran npm run build:docs locally and reviewed built documentation

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Documentation change

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [ ] I have updated docs/changelog.md