fix: conditionally adds aria-expanded to dropdown

[chpalac]

Pull request checklist

• Addresses an existing issue: Fixes #0000
• Include a change request file using $ yarn change

Description of changes

Aria recommendation is to conditionally add aria-expanded="true" to the trigger button. See https://www.w3.org/TR/wai-aria-practices/examples/listbox/listbox-collapsible.html

Focus areas to test

(optional)

[fabricteam]

📊 Bundle size report

_{🤖 This report was generated against 944dd049cce65b7b9af11e9bded706dea417f4d8}

[codesandbox-ci]

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Latest deployment of this branch, based on commit a922230:

Sandbox	Source
@fluentui/react 8 starter	Configuration
@fluentui/react-components 9 starter	Configuration

[size-auditor]

Asset size changes

Project	Bundle	Baseline Size	New Size	Difference
office-ui-fabric-react	fluentui-react-northstar-Dropdown	210.624 kB	210.664 kB	40 bytes

 Over Tolerance (1024 B)  Over Baseline  Below Baseline  New   Removed 1 kB = 1000 B

Baseline commit: 944dd049cce65b7b9af11e9bded706dea417f4d8 (build)

[fabricteam]

Perf Analysis (@fluentui/react)

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Dialog	mount	1400	2646	1000	Possible regression

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	992	973	5000
BaseButton	mount	982	980	5000
Breadcrumb	mount	2654	2734	1000
ButtonNext	mount	540	541	5000
Checkbox	mount	1740	1633	5000
CheckboxBase	mount	1494	1387	5000
ChoiceGroup	mount	5047	5022	5000
ComboBox	mount	1024	1006	1000
CommandBar	mount	10242	10341	1000
ContextualMenu	mount	8617	8579	1000
DefaultButton	mount	1247	1254	5000
DetailsRow	mount	3905	3921	5000
DetailsRowFast	mount	3915	3942	5000
DetailsRowNoStyles	mount	3758	3746	5000
Dialog	mount	1400	2646	1000	Possible regression
DocumentCardTitle	mount	160	184	1000
Dropdown	mount	3403	3387	5000
FluentProviderNext	mount	3876	3858	5000
FluentProviderWithTheme	mount	224	237	10
FluentProviderWithTheme	virtual-rerender	106	104	10
FluentProviderWithTheme	virtual-rerender-with-unmount	263	278	10
FocusTrapZone	mount	1856	1831	5000
FocusZone	mount	1836	1826	5000
IconButton	mount	1886	1845	5000
Label	mount	375	362	5000
Layer	mount	3076	3135	5000
Link	mount	499	503	5000
MakeStyles	mount	1831	1818	50000
MenuButton	mount	1547	1633	5000
MessageBar	mount	2076	2045	5000
Nav	mount	3451	3445	1000
OverflowSet	mount	1206	1273	5000
Panel	mount	2591	2544	1000
Persona	mount	894	889	1000
Pivot	mount	1555	1493	1000
PrimaryButton	mount	1393	1398	5000
Rating	mount	8368	8340	5000
SearchBox	mount	1428	1419	5000
Shimmer	mount	2691	2819	5000
Slider	mount	2027	2054	5000
SpinButton	mount	5258	5282	5000
Spinner	mount	443	430	5000
SplitButton	mount	3295	3300	5000
Stack	mount	527	527	5000
StackWithIntrinsicChildren	mount	1830	1814	5000
StackWithTextChildren	mount	4983	4974	5000
SwatchColorPicker	mount	11030	11221	5000
TagPicker	mount	2765	2694	5000
TeachingBubble	mount	13161	13277	5000
Text	mount	446	443	5000
TextField	mount	1440	1440	5000
ThemeProvider	mount	1223	1222	5000
ThemeProvider	virtual-rerender	631	616	5000
ThemeProvider	virtual-rerender-with-unmount	1972	1980	5000
Toggle	mount	890	839	5000
buttonNative	mount	145	140	5000

Perf Analysis (@fluentui/react-northstar)

Perf tests with no regressions

Scenario	Current PR Ticks	Baseline Ticks	Ratio
ListNestedPerf.default	636	568	1.12:1
AlertMinimalPerf.default	317	286	1.11:1
LabelMinimalPerf.default	443	403	1.1:1
SegmentMinimalPerf.default	385	353	1.09:1
TreeWith60ListItems.default	202	186	1.09:1
ChatWithPopoverPerf.default	436	404	1.08:1
SliderMinimalPerf.default	1893	1758	1.08:1
ButtonMinimalPerf.default	193	180	1.07:1
AvatarMinimalPerf.default	237	223	1.06:1
AttachmentMinimalPerf.default	180	172	1.05:1
BoxMinimalPerf.default	373	355	1.05:1
ButtonSlotsPerf.default	601	571	1.05:1
ChatMinimalPerf.default	708	673	1.05:1
ListCommonPerf.default	703	667	1.05:1
LoaderMinimalPerf.default	723	691	1.05:1
CarouselMinimalPerf.default	501	484	1.04:1
DividerMinimalPerf.default	400	386	1.04:1
FormMinimalPerf.default	454	437	1.04:1
HeaderMinimalPerf.default	391	376	1.04:1
LayoutMinimalPerf.default	401	384	1.04:1
AttachmentSlotsPerf.default	1185	1152	1.03:1
ChatDuplicateMessagesPerf.default	327	316	1.03:1
ListWith60ListItems.default	710	691	1.03:1
SplitButtonMinimalPerf.default	4616	4489	1.03:1
TooltipMinimalPerf.default	1113	1082	1.03:1
TreeMinimalPerf.default	847	825	1.03:1
ButtonOverridesMissPerf.default	1793	1756	1.02:1
CardMinimalPerf.default	613	602	1.02:1
CheckboxMinimalPerf.default	2780	2732	1.02:1
DatepickerMinimalPerf.default	5761	5658	1.02:1
ToolbarMinimalPerf.default	1010	988	1.02:1
VideoMinimalPerf.default	682	667	1.02:1
DropdownManyItemsPerf.default	760	751	1.01:1
InputMinimalPerf.default	1337	1327	1.01:1
MenuMinimalPerf.default	900	891	1.01:1
PopupMinimalPerf.default	622	616	1.01:1
ProviderMergeThemesPerf.default	1724	1703	1.01:1
RadioGroupMinimalPerf.default	482	477	1.01:1
SkeletonMinimalPerf.default	397	395	1.01:1
StatusMinimalPerf.default	733	725	1.01:1
TableManyItemsPerf.default	2107	2078	1.01:1
TextAreaMinimalPerf.default	563	558	1.01:1
CustomToolbarPrototype.default	4201	4171	1.01:1
AnimationMinimalPerf.default	420	419	1:1
DropdownMinimalPerf.default	3023	3033	1:1
EmbedMinimalPerf.default	4320	4300	1:1
ItemLayoutMinimalPerf.default	1278	1284	1:1
ListMinimalPerf.default	553	551	1:1
MenuButtonMinimalPerf.default	1725	1726	1:1
ReactionMinimalPerf.default	401	403	1:1
DialogMinimalPerf.default	787	796	0.99:1
TextMinimalPerf.default	366	371	0.99:1
ProviderMinimalPerf.default	1135	1155	0.98:1
RefMinimalPerf.default	236	241	0.98:1
RosterPerf.default	1285	1329	0.97:1
PortalMinimalPerf.default	179	184	0.97:1
FlexMinimalPerf.default	291	304	0.96:1
HeaderSlotsPerf.default	778	813	0.96:1
ImageMinimalPerf.default	420	436	0.96:1
IconMinimalPerf.default	649	673	0.96:1
AccordionMinimalPerf.default	170	182	0.93:1
TableMinimalPerf.default	430	462	0.93:1
GridMinimalPerf.default	341	370	0.92:1