fix(Popper): use keepTogether for arrow modifier

[layershifter]

Fixes #2360.

This PR enables keepTogether modifier in Popper for cases when we have pointer beaks.

Before

After

[DustyTheBot]

Perf comparison

Status	Scenario	Fluent TPI	Fabric TPI	Ratio	Iterations	Ticks
🔧	Avatar.Fluent	0.56	0.52	1.08:1	2000	1125
🦄	Button.Fluent	0.14	0.28	0.5:1	1000	136
🔧	Checkbox.Fluent	1.04	0.4	2.6:1	1000	1041
🔧	Dialog.Fluent	0.43	0.22	1.95:1	5000	2125
🔧	Dropdown.Fluent	4.93	0.41	12.02:1	1000	4925
🔧	Icon.Fluent	0.13	0.05	2.6:1	5000	645
🦄	Image.Fluent	0.05	0.08	0.63:1	5000	248
🔧	Slider.Fluent	1.51	0.35	4.31:1	1000	1514
🔧	Text.Fluent	0.07	0.02	3.5:1	5000	331
🦄	Tooltip.Fluent	0.13	19.28	0.01:1	5000	626

🔧 Needs work     🎯 On target     🦄 Amazing

Perf tests with no regressions

Scenario	Current PR Ticks	Baseline Ticks	Ratio
ImageMinimalPerf.default	319	261	1.22:1
AnimationMinimalPerf.default	558	460	1.21:1
StatusMinimalPerf.default	319	263	1.21:1
PopupMinimalPerf.default	390	328	1.19:1
FormMinimalPerf.default	1013	869	1.17:1
TooltipMinimalPerf.default	1086	935	1.16:1
BoxMinimalPerf.default	268	234	1.15:1
TableMinimalPerf.default	735	637	1.15:1
Dropdown.Fluent	4925	4275	1.15:1
ToolbarMinimalPerf.default	880	771	1.14:1
ButtonSlotsPerf.default	732	656	1.12:1
IconMinimalPerf.default	334	298	1.12:1
LoaderMinimalPerf.default	3090	2753	1.12:1
Dialog.Fluent	2125	1902	1.12:1
HeaderSlotsPerf.default	1739	1591	1.09:1
InputMinimalPerf.default	1099	1006	1.09:1
ReactionMinimalPerf.default	3169	2902	1.09:1
DividerMinimalPerf.default	1224	1133	1.08:1
ProviderMinimalPerf.default	639	592	1.08:1
TextMinimalPerf.default	291	269	1.08:1
AccordionMinimalPerf.default	202	188	1.07:1
ButtonMinimalPerf.default	131	124	1.06:1
LabelMinimalPerf.default	1136	1076	1.06:1
RadioGroupMinimalPerf.default	434	408	1.06:1
Image.Fluent	248	234	1.06:1
AlertMinimalPerf.default	629	597	1.05:1
ChatMinimalPerf.default	2289	2177	1.05:1
ChatDuplicateMessagesPerf.default	742	716	1.04:1
Checkbox.Fluent	1041	1005	1.04:1
Tooltip.Fluent	626	600	1.04:1
ChatWithPopoverPerf.default	781	756	1.03:1
DropdownMinimalPerf.default	4923	4785	1.03:1
GridMinimalPerf.default	1191	1161	1.03:1
DropdownManyItemsPerf.default	585	576	1.02:1
Tree60WithListItems.default	262	257	1.02:1
AttachmentMinimalPerf.default	949	943	1.01:1
MenuMinimalPerf.default	2300	2276	1.01:1
Text.Fluent	331	329	1.01:1
DialogMinimalPerf.default	2194	2184	1:1
ProviderMergeThemesPerf.default	1125	1127	1:1
Icon.Fluent	645	646	1:1
ListMinimalPerf.default	378	382	0.99:1
RefMinimalPerf.default	148	149	0.99:1
ListWith60ListItems.default	228	232	0.98:1
PortalMinimalPerf.default	216	220	0.98:1
SliderMinimalPerf.default	1517	1541	0.98:1
TextAreaMinimalPerf.default	3556	3638	0.98:1
CustomToolbarPrototype.default	4793	4878	0.98:1
HeaderMinimalPerf.default	475	491	0.97:1
Button.Fluent	136	140	0.97:1
SegmentMinimalPerf.default	1250	1303	0.96:1
CheckboxMinimalPerf.default	4554	4785	0.95:1
EmbedMinimalPerf.default	7872	8318	0.95:1
Slider.Fluent	1514	1599	0.95:1
SplitButtonMinimalPerf.default	13614	14545	0.94:1
HierarchicalTreeMinimalPerf.default	927	998	0.93:1
LayoutMinimalPerf.default	704	756	0.93:1
MenuButtonMinimalPerf.default	1588	1711	0.93:1
ListCommonPerf.default	942	1019	0.92:1
ListNestedPerf.default	841	919	0.92:1
FlexMinimalPerf.default	413	455	0.91:1
VideoMinimalPerf.default	787	877	0.9:1
AttachmentSlotsPerf.default	3258	3719	0.88:1
AvatarMinimalPerf.default	566	641	0.88:1
TreeMinimalPerf.default	914	1043	0.88:1
Avatar.Fluent	1125	1307	0.86:1
CarouselMinimalPerf.default	2245	2643	0.85:1
ItemLayoutMinimalPerf.default	1821	2145	0.85:1

Generated by 🚫 dangerJS