base option not support fully url at dev mode

Describe the bug

from #833, the last comment.

In my case, use base like this:

import { defineConfig } from "vite";
import vue from "@vitejs/plugin-vue";
export default defineConfig({
    plugins: [
        vue({
            template: {
                compilerOptions: {
                    isCustomElement: function(tag) {
                        return tag.includes("fl-") || tag.includes("sl-");
                    }
                }
            }
        })
    ],
    base: "http://localhost:3003/",
    root: "/Users/zhouyiming/Project/frameless-pc/src/pages/demo1"
});

But when i visit the http://localhost:3003/, the assets is not be rewrited

if this page is nested in a “main” page, this request will be 404

Reproduction

https://stackblitz.com/edit/vitejs-vite-ofxh2y?file=vite.config.js&terminal=dev

System Info

System:
    OS: macOS 12.3.1
    CPU: (8) arm64 Apple M1
    Memory: 97.41 MB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 18.0.0 - /opt/homebrew/bin/node
    npm: 8.6.0 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 102.0.5005.115
    Safari: 15.4
  npmPackages:
    vite: ^2.9.9 => 2.9.9

Used Package Manager

pnpm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn’t already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it’s a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[patak-dev]

One of the reasons that #8450 adds the options at build is to allow to do the same in the future for dev.advancedDevOptions. But the path there may be a bit long, and it is unclear to me at this point if the flexibility justifies the complexity at dev time. @Yiniau did you check https://vitejs.dev/config/#server-origin, this is what some backend integrations are using right now

[Yiniau]

you’re already serving the files via the url the vite dev server is on, e.g. localhost:3000.

actually, there are two servers is running,

1. the main server run in port 10000
2. the page server run in port 3000

that look like Single-SPA, if developer visit 3000, all be fine. but some assets will be 404 when they visit 10000.

if the url not change, any other config just helpless.