chore: add tsup bundling

[Julien-R44]

As discussed

The only concrete thing to do with tsup is to ensure that the package.json exports match the entrypoints specified in tsup config
I've also added validator as a bundled dependency. So yeah bundling dependencies should be done very sparingly because it can be a real headache. But in this case I think it's worth to do it as we've seen in different benchmarks :

Not bundled vs vine/vine + vine/compiler bundled

Not bundled vs vine/vine + vine/compiler + validator bundled

[thetutlage]

Hello 👋

Looks quite simple. I was going through the documentation of tsup and found a couple of notes we should look into.

Using tsup-node

Validating generated types

We should add this to our build pipeline

[Julien-R44]

issue with tsup-node is that it ignores even the "noExternal" property, which, in our case, allows validator.js to be bundled
But OK to use this by default everywhere, or even here if we decide to not bundle validator.js

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regarding the validation of generated types, I didn't found any good solutions for it. I tried @arethetypeswrong/cli but it has one major problem: arethetypeswrong/arethetypeswrong.github.io#45

it doesn't install dependencies. So, for example, in our ./types file for vine, we import some types from vine/compiler to define others ones :
https://github.com/vinejs/vine/blob/develop/src/types.ts#L18
So, for typescript to understand these types, you need to have vinejs/compiler installed. Something that attw does not do
and with tsc i'm not sure there's an easy and automated way of checking this

i've used tsup a bit on front-end libraries and I've never felt the need to do that, so i would say we can do without it
i've never encountered an error with invalid types generated