feat(arrow): Allow record batches output from read_sql

[chitralverma]

Changes

• Builds on the existing new_record_batch_iter to expose a pyarrow RecordBatchReader on python side
• Supports completely lazy iterations over arrow stream destination
• Added kwargs to read_sql, users can pass record_batch_size to control the number of records in each record batch.
• fixed a few unwraps causing issues
• Updates RecordBatchReader trait to support Send (helps offload RecordBatchReader to multi-threaded consumers like DuckDB)
• Left existing implementations as is, ideally those can also rely on record batch approach

Usage/ Example

import connectorx as cx

conn = "mysql://username:password@server:port/database/"
query = "SELECT * FROM employees"

rb_iter = cx.read_sql(
    conn,
    query,
    return_type="arrow_record_batches",
    record_batch_size=120333,
)

---

closes #278

[chitralverma]

is this okay or do you suggest any workarounds?

# doesn't work without `.clone()`, breaks with the following 

cannot move out of `self` which is behind a shared reference
move occurs because `self.0` has type `arrow::array::RecordBatch`, which does not implement the `Copy` trait

[chitralverma]

returns a pyarrow RecordBatchReader instead of an iterator/ generator of RecordBatch. I guess this will be useful for users who want to get the pyarrow Schema since RecordBatchReader has it.

[chitralverma]

@wangxiaoying for your review.
If this seems ok, I'll update the PR with documentation/ examples and such.

[wangxiaoying]

Thanks @chitralverma for the PR! I will take a look at it by the end of this week.