fix hx-location to handle replace

[MichaelWest22]

Description

With HX-Location you can disable the default push = 'true' it does with false but there is currently no way to enable the replace option I added documentation for earlier. While you can set push to 'false' this is still truthy and this blocks it picking up replace option. You can try using the boolean false but this just gets overwritten by 'true' right now.

So to fix this just need to use ?? instead of || so boolean false will prevent the 'true'. And also improve handling of 'false' by setting it to null so it won't block replace applying.

Corresponding issue:

Testing

Added a couple of tests for setting push to false and 'false' and setting replace.

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded

[1cg]

Thank you!