* fix: ElectronBrowserContext::PartitionKey comparisons

Use c++20 default comparisons to simplify + fix PartitionKey sorting:

- The equality operator is broken. `PartitionKey{"foo", false}` is both
  equal, to and less than, `PartitionKey{"foo", true}`

- For some keys, the same session can be retrieved via both `fromPath()`
  and `fromPartition()`. This use case was discussed and removed from
  the original PR after code review said "always returning different
  sessions feels lower maintenance." The current behavior is a bug that
  comes from the comparison operators not checking the keys' types.

Xref: https://github.com/electron/electron/pull/36728/commits/3f1aea9af91e17b2605eb8a5837bbb81888d76da#r1099745359

Xref: https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++-features.md#Default-comparisons-allowed



Co-authored-by: Charles Kerr <charles@charleskerr.com>

* fixup! fix: ElectronBrowserContext::PartitionKey comparisons

Co-authored-by: Charles Kerr <charles@charleskerr.com>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>