Fix various slugify() issues + add tests

[spacegaier]

Breaking change

Proposed change

Existing logic had various issues:

1. Only the first - was getting replaced => global flag added
2. The existing logic to prevent duplicate delimiters in the output was hard-coded to two consecutive instances => now replaced by a generic solution
3. The logic to trim any delimiter from the start of end was invalid and had no effect => fixed

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes Device entity ID renaming fails when old device name has at least two hyphens #10378
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io