Map: Add default baselayer to map when no mapConfig exists

[tkohr]

Description

This PR adds the default baselayer to the map even if no mapConfig exists. This case can occur in particular in custom applications without a config.

Quality Assurance Checklist

• Commit history is devoid of any merge commits and readable to facilitate reviews
• If new logic ⚙️ is introduced: unit tests were added
• If new user stories 🤏 are introduced: E2E tests were added
• If new UI components 🕹️ are introduced: corresponding stories in Storybook were created
• If breaking changes 🪚 are introduced: add the breaking change label
• If bugs 🐞 are fixed: add the backport <release branch> label
• The documentation website 📚 has received the love it deserves

This work is sponsored by MEL.

[github-actions]

Affected libs: feature-map, feature-dataviz, feature-record, feature-router,
Affected apps: metadata-editor, datahub, demo, webcomponents, search, map-viewer,

• 🚀 Build and deploy storybook and demo on GitHub Pages
• 📦 Build and push affected docker images

[coveralls]

coverage: 85.619% (+2.3%) from 83.342%
when pulling 796704d on basemap-no-config
into 1189d39 on main.

[cmoinier]

Changes look good, thanks for the work ! 😄