RUMM-2781: Remove duplication of UserInfo and NetworkInfo classes

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What does this PR do?

This change removes core models UserInfo and NetworkInfo in order to rely completely to the similar models from com.datadog.android.v2.api.context package in all the flows: SDK content retrieval, log generation, NDK crash handling, etc.

Serialization and de-serialization for UserInfo and NetworkInfo models are not auto-generated as for the models from core package, because there is no need to expose related methods to the public API (they are completely fine to be internal, because serialization and de-serialization is done only from the main module), and classes are not auto-generated as well, for the consistency with other classes from com.datadog.android.v2.api.context package.

Also some classes are moved out from log package to the core package, because they have nothing to do with Logs flow.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)