Modernize default template with better modern practices

[mnaoumov]

• Move TypeScript files into src folder.
• Encourage splitting into separate files.
• Don't encourage outdated node module type:

According to the spec: 1, 2:

You very likely want "nodenext" for modern Node.js projects.
You probably won’t need to use node10 in modern code.

• noemit as we don't need default tsc building (we use esbuild instead).
• allowImportingTsExtensions to have more accurate imports.

P.S. That's the bare minimum, I think we need encourage the plugin developers to use. If this gets approved, I can suggest even stricter settings to encourage even better practices.

P.S.2: To see what I have in mind: https://github.com/mnaoumov/obsidian-sample-plugin-extended/