feat: allow custom vite env prefix

[hyf0]

close #4194

Description

Additional context

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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.

[hyf0]

I'm not sure whether envVariblePrefix is a good name? I'm open to a better name.

[patak-dev]

My preference would be to use envPrefix. We can leave the final call to be discussed with the rest of the team though this week.

[Shinigami92]

I don't have strong opinion here, both names are okay

[hyf0]

Thanks for the suggestions. I'm changing to envPrefix for now and waiting for the final call.

[patak-dev]

ping @benmccann, just so you are aware of this new option in case it is useful for SvelteKit

[benmccann]

Thanks! This is nice. I like the idea of using something like PUBLIC or CLIENT since it always seemed a bit weird to me to put VITE in user code

[VojtechVitek]

This is great. Thank you!

Could we mention that envPrefix is available from Vite v2.5.2 in the documentation?

[patak-dev]

Could we mention that envPrefix is available from Vite v2.5.2 in the documentation?

We are not including the version when a feature has been added at this point in the documentation. IMO, since the project is young we can assume most of the people will be on latest fairly quickly. How to add this info to the docs and when should be discussed for all options at one point. The best way to see when features were added is to follow the changelog