Add tokenizer improvements via Singleton class and estimation

[timothycarambat]

Pull Request Type

• ✨ feat
• 🐛 fix
• ♻️ refactor
• 💄 style
• 🔨 chore
• 📝 docs

Relevant Issues

resolves #3069

What is in this change?

• Moves getEncoding function to a singleton type class to prevent multiple reallocation and initialization calls from uploading files or performance tracking chat text tokens.
• removes .length from tokenizeString calls since it now returns a number and not an array
• Will do approx string count estimation and at ~10kb of size we will do a simple mathmatical approximation
• Added JSDoc to functions as well

Additional Information

Developer Validations

• I ran yarn lint from the root of the repo & committed changes
• Relevant documentation has been updated
• I have tested my code functionality
• Docker build succeeds locally