feat: web worker based timers

[gavinbarron]

Closes #2820

PR Type

• Feature

Description of the changes

Adds a web worker based setInterval implementation

PR checklist

• Project builds (yarn build) and changes have been tested in at least two supported browsers (Edge + non-Chromium based browser)
• All public APIs (classes, methods, etc) have been documented following the jsdoc syntax
• Stories have been added and existing stories have been tested
• Added appropriate documentation. Docs PR:

• License header has been added to all new source files (yarn setLicense)
• Contains NO breaking changes

Other information

[microsoft-github-policy-service]

Thank you for creating a Pull Request @gavinbarron.

This is a checklist for the PR reviewer(s) to complete before approving and merging this PR:

• I have verified a documentation PR has been linked and is approved (or not applicable)
• I have ran this PR locally and have tested the fix/feature
• I have verified that stories have been added to storybook (or not applicable)
• I have tested existing stories in storybook to verify no regression has occured
• I have tested the solution in at least two browsers (Edge + 1 non-Chromium based browser)

[github-actions]

🚀 New react-contoso sample application deployed here

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
mgt-chat.src.statefulClient	100%	100%	0	✔
mgt-chat.src.utils	96%	88%	0	✔
mgt-components.src.components.mgt-person	56%	47%	0	➖
mgt-components.src.components.mgt-theme-toggle	100%	100%	0	✔
mgt-components.src.components.sub-components.mgt-flyout	30%	13%	0	❌
mgt-components.src.components.sub-components.mgt-spinner	100%	100%	0	✔
mgt-components.src.graph	19%	7%	0	❌
mgt-components.src.styles	96%	64%	0	✔
mgt-components.src.utils	40%	4%	0	❌
mgt-element.src	39%	0%	0	❌
mgt-element.src.components	30%	0%	0	❌
mgt-element.src.mock	51%	42%	0	➖
mgt-element.src.providers	39%	19%	0	❌
mgt-element.src.utils	43%	26%	0	❌
Summary	40% (791 / 1969)	20% (245 / 1209)	0	❌

[musale]

I've learnt a bunch of new APIs on this one. It looks good to go!

[gavinbarron]

@musale I got to learn a bunch on it too. I used a SharedWorker so that there is only one background thread per origin running no matter how many chat instances are open. A regular worker would have sufficed too, but I wanted to try out a SharedWorker.