Fix the theming to be compatible with Mkdocs 1.4.2

[Mariangela]

Description:

• Fix the theming to be compatible with Mkdocs 1.4.2
• Fix the doc search to be compatible with Mkdocs 1.4.2
• Look at using Mkdocs 1.4.2 with Python 3.11 (preferable) or 3.9

Summary of issues based on the docs in dev-apk

• Check the formatting in dev-APK docs #114

[chanaka3d]

Notes on the tasks in the list.

• Fixed the theming to be compatible with [Mkdocs 1.4.2]. this can be marked as done since the main part of the theming is done. We can treat other minor issues like tabs not rendered etc as separate tasks.

• Fix the doc search to be compatible with Mkdocs 1.4.2. This is done and the separate Jenkins build is also running smoothly.

• Look at using Mkdocs 1.4.2 with Python 3.11 (preferable) or 3.9. We went with Python 3.10 and the Readme is also updated accordingly.

[chanaka3d]

All the items listed here are fixed. Please check and confirm in the dev environment.