Bonus refactoring, part3 (save-incompatible)

[rilian-la-te]

Fixes #2125

Serialization version is bumped.

Changes:

1. Replaced BonusDuration from enum class to std::bitset (because duration is really flags, and not an enum, so, we need to be able to enable any durations combined)
2. 100% magic resistance and 100% spell damage reduction now should give a spell immunity to creature (to negative and damage spells respectively). Elemental damage 100% reduction should give immunity to any damage effects of this element, including non-magical. For now, works for any effect except maybe fire shield (need check). But fire shield and rebrith needs major rework, which is outside of scope of this PR.
3. Replaced (SCHOOL)_SPELL_DMG_PREMY with SPELL_DAMAGE bonus (subtype now is school). ANY subtype is used for sorcery skill.
4. Removed bonuses (SCHOOL)_SPELLS - replaced with SPELLS_OF_SCHOOL
5. Removed DIRECT_DAMAGE_IMMUNITY bonus (replaced by 100% spell damage resist in one place when it is used).
6. MAGIC_SCHOOL_SKILL changes subtype to be in line of other spell school bonuses. Now its subtype is school number directly, was be school number powered by two.
7. Allow to use spellSchool string identifier as subtype, which was be a motivation to change of 6.
8. Changed unit tests and added new unit tests according to this changes.

[Alucard648]

Will it be possible to limit teleporting for open field battles, if all paths to destination hex are blocked by obstacles and creatures?
Also hoping for placeable obstacle placing spells.

[rilian-la-te]

@Alucard648 what you mean by placeable obstacle placing spells?

[Alucard648]

H5 obscacle creating spells, like Arcane Crystal, Blade Barrier, controllable quicksand/landmine spells etc. And idea for Summon elemental spell - ability to place summoned creature at chosen location.

[rilian-la-te]

@Alucard648 this is not obstacles, this is an immobile creatures.