Allow the main entry type button to be translatable

[joostlek]

## Proposed change

So some integrations are considered a service or hub and the frontend will show "Add service" or "Add hub". While in reality, for example in the case of Spotify, it's not a service they add, but rather an account, so this PR allows integrations to overwrite this button's text, so you can change it to "Add account" to make it more user friendly :)
core PR:
home-assistant/core#159901

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 #
• 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