Hosting dashboard: clean up Staging Site tab

[fushar]

Part of:

• https://github.com/Automattic/dotcom-forge/issues/7924

Proposed Changes

This PR refactors the code for the hosting dashboard's Staging Site tab, by moving them under client/hosting/staging-site/ directory.

Why are these changes being made?

Consistency and to avoid future confusion.

Testing Instructions

1. Go to /sites.
2. Select an Atomic site.
3. Click the Staging Site tab.
4. Smoke test and verify that the feature still works.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-119324

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-119324&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-119324&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

App Entrypoints (~3 bytes removed 📉 [gzipped])

name           parsed_size           gzip_size
entry-stepper        +16 B  (+0.0%)       -2 B  (-0.0%)
entry-main           +16 B  (+0.0%)       -2 B  (-0.0%)

Common code that is always downloaded and parsed every time the app is loaded, no matter which route is used.

Sections (~52 bytes added 📈 [gzipped])

name                parsed_size           gzip_size
staging-site             +177 B  (+0.0%)      -20 B  (-0.0%)
activity                  -32 B  (-0.0%)      +72 B  (+0.0%)
sites-dashboard           -16 B  (-0.0%)       -5 B  (-0.0%)
site-performance          -16 B  (-0.0%)       -5 B  (-0.0%)
site-monitoring           -16 B  (-0.0%)       -5 B  (-0.0%)
site-logs                 -16 B  (-0.0%)       -5 B  (-0.0%)
hosting-features          -16 B  (-0.0%)       -5 B  (-0.0%)
hosting                   -16 B  (-0.0%)       -5 B  (-0.0%)
github-deployments        -16 B  (-0.0%)       -5 B  (-0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug refactor-staging-site-tab on your sandbox.

[nightnei]

LGTM and works as previously 👍