Add support for arrays as argument

[dcastil]

From discussion:

The more I'm thinking about this, the more I think I should include clsx in tailwind-merge. My reasons:

1. clsx (or its pendant classnames) is probably already included in most projects using tailwind-merge. I have copied parts of clsx and inlined it in tailwind-merge to join strings, so adding it would have almost no impact on bundle size nor runtime performance.

2. I find the pattern of nested conditions with arrays in clsx really nice and often miss it in tailwind-merge. Basically this:

   clsx('…', someBool && ['…', anotherBool && '…'])

3. Prepending twMerge with clsx myself is not so nice DX-wise, even when using tailwind-merge with a custom config. It can even lead to anti-patterns.

   // This feels a little weird
   const twMergeInternal = extendTailwindMerge(…)
   export const twMerge = (...args) => twMergeInternal(clsx(args))
   
   // I really hope no one is doing this!
   export const twMerge = (...args) => extendTailwindMerge(…)(clsx(dontDoThis!))

I think I'll give it a shot. And if it turns out not to be a good idea, I think tailwind-merge should go into the opposite direction in a v2 update and only accept a single string as argument. This way the user could choose their own string-joining lib and tailwind-merge would leave the weird middle ground it is on right now.

Originally posted by @dcastil in #121 (reply in thread)

[dcastil]

I definitely want to support arrays and nested arrays. I don't like objects but would probably be too opinionated not to support them.

[dcastil]

There is additional new context in #121, should check that out before working on this.

[github-actions]

This was addressed in release v1.6.0.