Add Token filter pages for common_grams, conditional and decimal_digit[DOC]

[AntonEliatra]

What do you want to do?

• [ ] Request a change to existing documentation
• [x] Add new documentation
• [ ] Report a technical problem with the documentation
• [ ] Other

Create a separate page for Token filter for:

• [ ] - common_grams
• [ ] - conditional
• [ ] - decimal_digit

Part of META issue: https://github.com/opensearch-project/documentation-website/issues/1483

*Version: all

[AntonEliatra]

@hdhalter I can take this one

[Naarcha-AWS]

@AntonEliatra: Assigned to you.