fix: Allow custom asset URL origin in development

[innocenzi]

Description

This PR fixes the issue where, with a custom back-end, the URLs of the assets during development were stripped of their origin, resulting in 404s because the app URL is different than Vite's dev server URL.

#4337 (comment)

To sum up the issue:

• A page is loaded at http://custom-url.test
• This page loads an asset, image.png
• In development, this asset's path is stripped from its origin by Vite, resulting in http://custom-url.test/image.png instead of http://localhost:3000/image.png

This implementation solves the issue by allowing us to define an origin (server.publicPath), so the > resulting generated asset URL will be the right one.

The build part was working as expected already, this implementation only changes the development one, so this is what we needed.

Additional context

This is a fork of @2359634711's fix with the review taken into account.

This PR:

• Closes fix: Allow custom URL prefix in CSS #4337
• Fixes how can I set the publicPath in runtime , just like webpack set webpack_public_path at the entry, it is very important for me ! #3070
• Fixes 建议增加publicPath配置参数，用于部署应用包时的基本 URL，同vue-cli中的publicPath配置一样 #3646
• Fixes CSS full path for images #1539
• Fixes Importing Asset as URL strips the host in the base option #4942
• Fixes Absolute path for assets in development mode, allowing correct paths when app is added to legacy website #2394
• Fixes vite dev can't set base url like vite build #2714

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Merging as this was already approved in our last meeting

[jianqi-jin]

@innocenzi Thanks, great job.