feat: support for numeric separators in revalidate config (#51438)
### Fixing a bug
- [x] Related issues linked using `fixes #number`
- [x] Tests added. See:
https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs
- [ ] Errors have a helpful link attached, see
https://github.com/vercel/next.js/blob/canary/contributing.md
### What?
Currently, when the check on validating the type of `revalidate` is run,
we use the `Number` function to parse the value of `revalidate`, however
the `Number` function takes a
[`StringNumericLiteral`](https://tc39.es/ecma262/2023/#prod-StringNumericLiteral)
which doesn't allow the usage of the `_` separator to format your
numbers. This PR allows you to add numeric separators in the
`revalidate` export.
### Why?
When configuring the actual code, we should be allowed to use numeric
separators as it is a syntax that is supported by most runtimes.
### How?
A simple `replaceAll` call that removes all `_`s between digits.
Closes NEXT-1122
Fixes #49485
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Co-authored-by: JJ Kasper <jj@jjsweb.site>