Add a character/word limits/requirements to Summarize text

Problem/Motivation

When using the Summarize text in openai_content it would be helpful to be able to specify the number of characters or words returned in the summary. This feature would be useful when you want to populate a field that has a character limit or when you're creating content for social media.

Steps to reproduce

Enabled submodule openai_content, create a node, open the Summarize text, select a field to summarize. If the field has a large amount of content, the summary can be very long.

Proposed resolution

Add configuration options to allow users to select the maximum and/or minimum number of characters or words.

User interface changes

Add fields in the Summary text section:

1. Characters or words (select list)
2. Minimum length (number)
3. Maximum length (number)