Capif aef security api (#5)

PR:

AEF security implementation within the provider api publication and invoker,
Documentation updated,
Fixed little mistakes related to renaming, loading initial data, etc,
Tests modified,
License Apache 2 for ETSI added.

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