Add enable cost monitoring button

[mendaomn]

Description

This PR adds a button to enable cost monitoring for the current account. It handles the following scenarios:

• PC supports cost monitoring
• PC supports cost monitoring, but Cost Explorer has not been activated on the console yet
• PC does not support cost monitoring

In order to reduce calls to CostExplorer to a minimum, the cost monitoring status is optimistically set to true in case of success, instead of calling the GetCostMonitoringStatus again

This PR builds upon the work done with #195 . Even though #195 isn't 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 cost_monitoring and experimental feature flag
• add button to enable cost monitoring
• add commands and mutation to get the current status and activate cost monitoring

Screenshots

How Has This Been Tested?

• manually, by mocking backend responses
• manually, by integrating locally with #195 and checking that interactions work as expected
• unit tests

PR Quality Checklist

• [x] I added tests to new or existing code
• [x] 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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