Fetch restore progress details from /restore endpoint

[monsieur-z]

Changes proposed in this Pull Request

This PR is a sequel of #47153. It retrieves data from a different endpoint in order to show more granular percentage and to display the entry being restored.

Testing instructions

• Run this PR in Calypso or Jetpack cloud
• Select a self-hosted Jetpack site that has a Backup product, and more than one backup
• Make sure you have set server credentials to enable restores
• Visit the Backup section, select a backup to restore, and click Restore to this point, the Confirm restore
• Check that you see the message and current entry returned by the API, respectively above and below the progress bar
• Make sure the order of messages makes sense and that there's no big jump in the progress bar

[matticbot]

Test live: https://calypso.live/?branch=improve/restore-progress-change-endpoint

[matticbot]

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

App Entrypoints (~10 bytes added 📈 [gzipped])

name        parsed_size           gzip_size
entry-main        +30 B  (+0.0%)      +10 B  (+0.0%)

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

Sections (~21 bytes added 📈 [gzipped])

name      parsed_size           gzip_size
backup         +823 B  (+0.2%)      +32 B  (+0.0%)
activity       +670 B  (+0.1%)      -11 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.

Async-loaded Components (~21 bytes added 📈 [gzipped])

name                                    parsed_size           gzip_size
async-load-signup-steps-rewind-migrate        +34 B  (+0.1%)       +7 B  (+0.1%)
async-load-signup-steps-clone-ready           +34 B  (+0.1%)       +7 B  (+0.1%)
async-load-signup-steps-clone-point           +34 B  (+0.0%)       +7 B  (+0.0%)

React components that are loaded lazily, when a certain part of UI is displayed for the first time.

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.

[elliottprogrammer]

This is awesome @monsieur-z ! Works great! Code looks great!
LGTM! 🚢