Port 'Updated ComboBox error to have role="alert"' to 7.0

[GeoffCoxMSFT]

Pull request checklist

• Addresses an existing issue: Fixes ComboBox error message has incorrect role for ARIA #20012
• [ X Include a change request file using $ yarn change

Description of changes

Port to 7.0 of the following:
Updated ComboBox error message to be consistent with DropDown (correct ARIA approach)

• Updated to be role="alert"
• Updated div to be added/removed with error message
• Removed aria live and atomic attributes
• Removed applying aria hidden when no error message

Focus areas to test

ComboBox

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 29dc6a7:

Sandbox	Source
Fluent UI Button	Configuration
codesandbox-react-template	Configuration

[size-auditor]

Asset size changes

Project	Bundle	Baseline Size	New Size	Difference
office-ui-fabric-react	office-ui-fabric-react-ComboBox	240.846 kB	240.787 kB	-59 bytes

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

Baseline commit: 67e037aa230a4f16a3734ea57e3a526965a2675d (build)

[fabricteam]

Perf Analysis

No significant results to display.

All results

Scenario	Render type	7.0 Ticks	PR Ticks	Iterations	Status
BaseButton	mount	767	751	5000
Breadcrumb	mount	36121	33299	5000
Checkbox	mount	1302	1327	5000
CheckboxBase	mount	1057	1075	5000
ChoiceGroup	mount	4145	4136	5000
ComboBox	mount	785	749	1000
CommandBar	mount	6473	6305	1000
ContextualMenu	mount	11497	12284	1000
DefaultButton	mount	956	944	5000
DetailsRow	mount	3085	3160	5000
DetailsRowFast	mount	3117	3120	5000
DetailsRowNoStyles	mount	2900	3058	5000
Dialog	mount	1391	1447	1000
DocumentCardTitle	mount	1554	1583	1000
Dropdown	mount	2088	2097	5000
FocusTrapZone	mount	1471	1483	5000
FocusZone	mount	1540	1539	5000
IconButton	mount	1432	1419	5000
Label	mount	252	282	5000
Layer	mount	1620	1638	5000
Link	mount	380	364	5000
MenuButton	mount	1230	1230	5000
MessageBar	mount	1715	1656	5000
Nav	mount	2772	2777	1000
OverflowSet	mount	1176	1197	5000
Panel	mount	1222	1231	1000
Persona	mount	669	660	1000
Pivot	mount	1258	1201	1000
PrimaryButton	mount	1068	1084	5000
Rating	mount	6645	6626	5000
SearchBox	mount	1085	1057	5000
Shimmer	mount	2146	2185	5000
Slider	mount	1260	1267	5000
SpinButton	mount	4003	4127	5000
Spinner	mount	351	347	5000
SplitButton	mount	2697	2681	5000
Stack	mount	426	378	5000
StackWithIntrinsicChildren	mount	1460	1471	5000
StackWithTextChildren	mount	3838	4013	5000
SwatchColorPicker	mount	8851	15412	5000
TagPicker	mount	2370	2360	5000
TeachingBubble	mount	43386	43456	5000
Text	mount	351	359	5000
TextField	mount	1175	1173	5000
Toggle	mount	703	698	5000
button	mount	96	87	5000

[msft-fluent-ui-bot]

🎉office-ui-fabric-react@v7.177.1 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes
• Official NPM Release
• Test the release with Developer Demo Site

[msft-fluent-ui-bot]

🎉@uifabric/fabric-website@v7.17.10 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes
• Official NPM Release

[msft-fluent-ui-bot]

🎉@uifabric/fabric-website-resources@v7.10.10 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes
• Official NPM Release

[msft-fluent-ui-bot]

🎉@uifabric/experiments@v7.40.9 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes
• Official NPM Release

[msft-fluent-ui-bot]

🎉@fluentui/react-examples@v0.15.10 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes
• Official NPM Release