Add initial project storage ui

What does this MR do?

Relates to #334885, #334886, #334887

This MR adds the initial UI for the Project Storage, being it the headline (#334885) and table (#334886, #334887)

There were a lot of discussions in the initial design and in the epic, and some decisions were made that don't reflect what you see in the design, so I'll summarize them here 😇

• In this first iteration, we will simplify the design to condense the storage by category into one bar and one table of data, because Repository Storage is just 1 item in the storage statistics and cannot be broken down into subitems as the design suggests
  • GraphQL field reference: ProjectStatistics
• Since we have 1 table and 1 bar now, we haven't decided on what to put in the headline (title + subtitle + learn more link + total storage used). So in this implementation I just copied what we have in the Group usage quotas. This decision was based on the epic description which states "We should re-use the view as-is for the first iteration and then build on that to improve the storage view in both the group level and the project level."
• Icons or not: "Let's keep it minimal since there isn't a clear direction yet and proceed without icons. We can add them as a follow-on iteration shortly after." https://gitlab.com/gitlab-org/gitlab/-/issues/321429/designs/initial.png#note_599268344
• Description for storage type: https://gitlab.com/groups/gitlab-org/-/epics/6264#note_615221560
• Where should the link for the storage type go: We haven't decided yet (https://gitlab.com/gitlab-org/gitlab/-/issues/321429/designs/initial.png#note_609925769) And we don't know that we have a "how to reduce the size" topic for each of these storage types (https://gitlab.com/groups/gitlab-org/-/epics/6264#note_615221549) "So in the design, I think these can probably just be question marks next to each storage type."

Screenshots or Screencasts (strongly suggested)

Group Usage Quotas (inspiration page)	Project Usage Quotas

How to setup and validate locally (strongly suggested)

1. Enable project_storage_ui feature flag. Go to rails console and execute the following:

   Feature.enable(:project_storage_ui)

2. Visit /<namespace>/<project>/-/usage_quotas on a project you have maintainer permission

Does this MR meet the acceptance criteria?

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