PR:
* SDK packaging in pypi repositories to install via pip opencapif_sdk atifact and simple import commands,
* OpenCAPIF SDK installation process clarified and updated,
* Pictures of OpenCAPIF flows adjusted,
* Updated scripts and test to new installation process,
* Updated general documentation,
* Small mistakes and typos fixed.

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Co-authored-by: Daniel García <daniel.garciasanchez@telefonica.com>
Co-authored-by: JorgeEcheva26 <jorge.echevarriauribarri.practicas@telefonica.es>

PR:
- Included complete Network App samples,
- Complete developer path description,
- Refactored code structure,
- Complete doc upgrade.

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Co-authored-by: JorgeEcheva26 <jorge.echevarriauribarri.practicas@telefonica.es>
Co-authored-by: Daniel García <daniel.garciasanchez@telefonica.com>