Docs: improve project introduction

[sidhansu10]

This PR improves the GDAL project introduction in the GitHub README by adding a more user-focused, example-driven overview of the project.
Changes include:

1. Clear description of what GDAL is and where it is used
2. Key features overview
3. Simple Python and C++ examples
4. Improved organization of documentation and resource links
   This addresses Issue Doc: Improve project introduction #12096.

[jratike80]

This PR would remove, without any prior discussion, whole lot of things from the launch page of the github project, for exampe the build status tags. And why changes into apps/ogr2ogr_lib.cpp‎ are included?

We have an introduction to the project in https://gdal.org/en/stable/. Maybe that could be inproved instead. The issue #12096 compares GDAL with QGIS, but I am not sure if it is good for QGIS to have user oriented introductions in two places (qgis.org and https://github.com/qgis/qgis). Why don't they use README.md for developer oriented things, and provide a link to qgis.org for user oriented things?

[coveralls]

coverage: 71.58% (-0.003%) from 71.583%
when pulling 9a061eb on sidhansu10:docs-improve-readme-intro
into cd71f9f on OSGeo:master.

[pramsey]

This is not responsive to the cited issue, which is about changing the gdal.org front page, not the github README. (Also, changes to ogr2ogr.cpp should be in separate PR with discussion.)