Build tasks: Namespace tasks for import into workspaces

[colinrotherham]

This PR exports all our build tools as groups:

1. Assets (writing to disk, JSDoc types)
2. Browser (download, launch, screenshots)
3. Configs (writing to JSON)
4. Files (delete, copy, versioning)
5. npm (running npm scripts from JS)
6. Scripts (compiling JS)
7. Styles (compiling Sass)

This lets us reuse tasks in the Review app to support:

• Split project into separate app, config, lib and tasks packages #2886

Before

Each task was a separate import

import { clean } from './tasks/clean.mjs'
import { compileConfig } from './tasks/compile-configs.mjs'
import { compileJavaScripts } from './tasks/compile-javascripts.mjs'
import { compileStylesheets } from './tasks/compile-stylesheets.mjs'
import { version } from './tasks/file.mjs'
import { copyAssets, copyFiles } from './tasks/gulp/copy-to-destination.mjs'
import { watch } from './tasks/gulp/watch.mjs'
import { npmScriptTask } from './tasks/run.mjs'

// Compile GOV.UK Frontend JavaScript (AMD modules)
compileJavaScripts('**/!(*.test).mjs', {
  srcPath: join(paths.src, 'govuk'),
  destPath: join(paths.package, 'govuk'),

  filePath (file) {
    return join(file.dir, `${file.name}.js`)
  }
}),

After

Each task is now part of a namespace

import { browser, files, scripts, styles, npm } from './tasks/index.mjs'

// Compile GOV.UK Frontend JavaScript (AMD modules)
scripts.compile('**/!(*.test).mjs', {
  srcPath: join(paths.src, 'govuk'),
  destPath: join(paths.package, 'govuk'),

  filePath (file) {
    return join(file.dir, `${file.name}.js`)
  }
}),

[romaricpascal]

question This is the only file that does a named import from index.mjs, I think. Why are the actual tasks not imporing from index.mjs (for consistency both of method and names)?

[colinrotherham]

I think just to avoid potential circular dependency issues in future. Happy to change it

[colinrotherham]

How's this? 712fa61