Expose the number of generated tokens for FreePromptProvider as an admin setting

[MB-Finski]

Describe the feature you'd like to request

Currently the responses from the text processing provider are limited to 100 tokens due to a hardcoded limit in FreePromptProvider.php. I'd propose exposing it as an admin option.

Describe the solution you'd like

Expose the token limit for FreePromptProvider.php as an admin option.

Describe alternatives you've considered

One alternative could be to provide the consumer of the FreePromptProvider with the ability request a token limit. However, I believe this would be a breaking change given the current architecture of text processing provider tasks. Therefore, introducing a new "v2" freeprompt task type would be necessary..?