Reorganize frontend files: move wcdl and external-components into components

[eason9487]

Changes proposed in this Pull Request:

Closes #195

This PR further reorganizes frontend files within two directories:

• js/src/wcdl
  • Move all sub-directories to the components directory and delete the README file
  • Rename the SelectControl component to SearchableSelectControl to differentiate it from AppSelectControl
    • AppSelectControl based on SelectControl from @wordpress/components
    • SearchableSelectControl based on SelectControl from @woocommerce/components
  • Rename the prefix wcdl- to gla- for all related CSS classes
• js/src/external-components
  • Move all sub-directories and files to the components/external directory

💡 I will likely skip code review since this PR only includes developer-facing change.

Screenshots of the directory structure:

📁 js/src/wcdl

Before	After
js/src/wcdl ├── README.md ├── radio-helper-text ├── section │ └── card ├── select-control └── subsection	js/src/components ├── radio-helper-text ├── searchable-select-control ├── section │ └── card └── subsection

📁 js/src/external-components

Before	After
js/src/external-components ├── README.md ├── woocommerce │ ├── compare-filter │ ├── filter-picker │ └── filters └── wordpress └── guide	js/src/components/external ├── README.md ├── woocommerce │ ├── compare-filter │ ├── filter-picker │ └── filters └── wordpress └── guide

Detailed test instructions:

1. Confirm npm run dev can build frontend code without errors
2. Confirm npm run lint:js can pass
3. Confirm npm run lint:css can pass
4. Confirm npm run test:js can pass
5. Confirm E2E tests can pass: https://github.com/woocommerce/google-listings-and-ads/actions/runs/12292309693

Additional details:

Over the past three to four years, the component development of the WooCommerce Design Library has stalled in this project for a long time and has become mismatched with the later evolution of the WooCommerce Design Library, so it may not be necessary to keep the original purpose and the wcdl directory.

See: p1694792606788619-slack-C05BG9S6B96

Changelog entry

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 63.4%. Comparing base (9db814e) to head (b9b2831).
Report is 10 commits behind head on develop.

Files with missing lines	Patch %	Lines
.../src/components/searchable-select-control/index.js	33.3%	2 Missing ⚠️
...bute-mapping/attribute-mapping-category-control.js	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2722   +/-   ##
=======================================
  Coverage     63.4%   63.4%           
=======================================
  Files          338     338           
  Lines         5203    5203           
  Branches      1274    1274           
=======================================
  Hits          3301    3301           
  Misses        1728    1728           
  Partials       174     174           

Flag	Coverage Δ
js-unit-tests	63.4% <62.5%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
js/src/components/account-card/index.js	89.2% <ø> (ø)
js/src/components/conditional-section.js	12.5% <ø> (ø)
...mponents/external/wordpress/guide/finish-button.js	0.0% <ø> (ø)
...s/src/components/external/wordpress/guide/icons.js	50.0% <ø> (ø)
...s/src/components/external/wordpress/guide/index.js	63.0% <ø> (ø)
...omponents/external/wordpress/guide/page-control.js	0.0% <ø> (ø)
...choose-audience-section/choose-audience-section.js	33.3% <ø> (ø)
...onfigure-product-listings/shipping-time-section.js	50.0% <ø> (ø)
...gure-product-listings/shipping-time-setup/index.js	20.0% <ø> (ø)
...ee-listings/configure-product-listings/tax-rate.js	33.3% <ø> (ø)
... and 35 more