[FEATURE REQUEST] Add warning in http connections

[joragua]

Related Issues

App: https://github.com/owncloud/android/issues/4284

• [x] Add changelog files for the fixed issues in folder changelog/unreleased. More info here
• [x] Add feature to Release Notes in ReleaseNotesViewModel.kt creating a new ReleaseNote() with String resources (if required)

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QA

[jesmrec]

QA checks

• [X] http server: warning displayed
• [X] http server: continue
• [X] http server: cancel
• [X] URL check after 40x
• [x] https non-secured: certificate warning (existing behaviour)
• [x] https secured: no warning

[jesmrec]

Approved