multi pages config

[rayfalling]

What problem does this feature solve?

multi pages config may lead error URIError: Failed to decode param '/%3C%=%20BASE_URL%20%%3Efavicon.ico' when no filename is set to index.html, may add the config to custom the entry page name(such as main.html?

What does the proposed API look like?

pages: {
student: {
entry: 'main/main.js',
template: 'public/main.html',
filename: 'student.html',
mainEntry:true,
chunks: ['chunk-vendors', 'chunk-common', 'main']
}
}

[haoqunjiang]

when no filename is set to index.html

Do you have a reproduction for this issue?

[rayfalling]

related to #4856
and I'll provide the repo soon

[rayfalling]

repo https://git.rayfalling.com/rayfalling/vue-cli-error-repo