[Fix] Unify dataclasses under a types.py for ease

[bhavnicksm]

This pull request focuses on refactoring the Chonkie package by moving several dataclass definitions to a new types module and updating the imports across various files accordingly. The most important changes include the relocation of dataclasses, the update of imports, and the addition of new attributes to certain classes.

Refactoring and code organization:

• src/chonkie/__init__.py: Moved Context, SemanticSentence, Sentence, Chunk, SentenceChunk, and SemanticChunk imports to the new types module.
• src/chonkie/chunker/__init__.py: Updated imports to reflect the relocation of Chunk, SemanticChunk, SemanticSentence, and Sentence to the types module.
• src/chonkie/chunker/base.py: Removed the Chunk dataclass and imported it from the types module instead.
• src/chonkie/types.py: Added a new module to house the Context, Chunk, Sentence, SentenceChunk, SemanticSentence, and SemanticChunk dataclasses.

Class and method updates:

• src/chonkie/chunker/sentence.py: Added a new attribute use_approximate to the SentenceChunker class and updated the constructor to include this attribute. [1] [2]

Test updates:

• Updated test files to import Chunk and SemanticChunk from the new types module. [1] [2] [3]