[Fix] Allow for functions as token_counters in BaseChunkers

[bhavnicksm]

This pull request includes several changes to the src/chonkie/chunker/base.py file to improve the handling of different tokenizer backends and provide more informative error messages. The most important changes include adding the inspect module to check if an object is a function, updating the initialization logic to handle different types of tokenizers, and enhancing the error messages to include the unsupported tokenizer backend type.

Improvements to tokenizer handling:

• Added import of inspect module to check if an object is a function. (src/chonkie/chunker/base.py)
• Updated the __init__ method to first check if the tokenizer_or_token_counter is a string, then check if it is a function using inspect.isfunction, and finally assume it is a tokenizer object if neither condition is met. (src/chonkie/chunker/base.py)

Enhanced error messages:

• Updated the _get_tokenizer_backend method to include the unsupported tokenizer backend type in the error message. (src/chonkie/chunker/base.py)
• Updated the _encode, _encode_batch, _decode, and _decode_batch methods to include the unsupported tokenizer backend type in the error messages. (src/chonkie/chunker/base.py) [1] [2] [3] [4]