WIP: improve startup time on mobile platform

removed some qml code and handwritten a new model to replace QSortFilterProxyModel's. Now the startup time on pinephone is about 3s. Previously is about 5-6s

Needs more test though.

Some changes in this:

• replace time selector from kirigami-addons with a simpler one, to avoid load plugin
• remove page transition animation (not sure, maybe isn't affect performance that much)
• unwrap loop -- repeater created toolbutton (about 50ms speedup on PC)
• hardcode width and height (about 3ms on PC, maybe not needed)
• load initial page at first (not sure)
• replace QSortFilterProxyModel (1.6s on pinephone)