Add Cluster Costs experimental page

[mendaomn]

Description

This PR adds a page reachable via the cluster actions, which shows the cost data for the selected cluster.

In order to reduce calls to Cost Explorer to a minimum, the staleTime of the queries is set to Infinity, thus new data is getting fetched only on page reload.

This PR builds upon #204 . Even though it is not merged yet, this is safe to merge as it is being protected by a feature flag.

Please note: copy is not definitive and hasn't been reviewed yet

Changes

• add new cluster action to View Costs
• add new /costs page
• set staleTime of queries to Infinity

Screenshots

How Has This Been Tested?

• manually, by mocking backend responses
• manually, by integrating locally with #204 and checking that data is graphed as expected
• unit tests

PR Quality Checklist

• [x] I added tests to new or existing code
• [ ] I removed hardcoded strings and used react-i18next library (useTranslation hook and/or Trans component), see an example here
• [ ] I made sure no sensitive info gets logged at any time in the codebase (see here) (e.g. no user info or details, no stacktraces, etc.)
• [ ] I made sure that any GitHub issue solved by this PR is correctly linked
• [ ] I checked that infrastructure/update_infrastructure.sh runs without any error
• [x] I checked that npm run build builds without any error
• [x] I checked that clusters are listed correctly
• [ ] I checked that a new cluster can be created (config is produced and dry run passes)
• [ ] I checked that login and logout work as expected

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