[7.x] [Stack Monitoring] Add initial react app (#109218)

[estermv]

Backports the following commits to 7.x:

• [Stack Monitoring] Add initial react app ([Stack Monitoring] Add initial react app #109218)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 85d6537
• Storybooks Preview

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
monitoring	565	570	+5

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
monitoring	725.5KB	757.4KB	+32.0KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
monitoring	45.4KB	45.9KB	+443.0B

Unknown metric groups

async chunk count

id	before	after	diff
monitoring	1	3	+2

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@elasticmachine merge upstream