DolphinView: distinguish programmatic and user generated activations

When switching tabs with split view enabled and the filter bar visible, a storm of activation calls is triggered and at the end signal/slot connections for both views is a mess (no listeners, navigation buttons linked to unfocused view etc.). As a solution a m_activatingProgrammatically guard flag to DolphinTabPage is added and all programmatic calls are wrapped to set it, thus allowing to distinguish if activate call came from user interaction or programmatically (tab switch, restore, etc.).

As most of related bugs are hard to reproduce, here is a list of bugs most likely fixed by this commit. BUG: 508554, BUG: 509525, BUG: 512011, BUG: 508405, BUG: 511076, BUG: 503576

Debugging and crafting of code was performed with Claude Opus 4.6