[RFC]: add `symbol/split`

### Description

This RFC proposes adding the package `symbol/split`.

The package should be very similar to the following existing packages:

- `symbol/has-instance`
- `symbol/iterator`
- `symbol/async-iterator`
- `symbol/is-concat-spreadable`

The primary difference is that the package should export `Symbol.split` if it exists.

### Related Issues

None.

### Questions

No.

### Other

When adding this package, one should do the following:

- copy one of the existing packages mentioned above
- rename the copied package
- find and replace the package name (e.g., `has-instance` => `split`)
- find and replace the variable name (e.g., `HasInstanceSymbol` => `SplitSymbol`)
- ensure the copyright years are 2025
- update the descriptions according to the symbol's purpose (see MDN)
- update examples to reflect the symbol's purpose (see existing packages for inspiration)
- run tests, benchmarks, and examples to ensure that everything passes
- go back through and check that there are no copy-paste mistakes

### Checklist

- [x] I have read and understood the [Code of Conduct](https://github.com/stdlib-js/stdlib/blob/develop/CODE_OF_CONDUCT.md).
- [x] Searched for existing issues and pull requests.
- [x] The issue name begins with `RFC:`.

Start by comparing symbol/has-instance, symbol/iterator, symbol/async-iterator, and symbol/is-concat-spreadable to identify the package structure, tests, benchmarks, and examples to copy. Check MDN for Symbol.split and update the copied package's descriptions and examples accordingly. Done means the new symbol/split package exports Symbol.split when available, has updated 2025 copyright years, and its tests, benchmarks, and examples pass.

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