feat: Support changes of options snapshots and chain

[hiohiohio]

Incompatible changes:

• get_option_snapshot returns OptionsSnapshot instead of Snapshot
• get_option_chain returns OptionsSnapshot instead of Snapshot

Context:

• the options snapshot and options chain API endpoints returns options greeks and implied volatility
• the options chain api endpoint accept new parameters to filter options contracts
• this PR support those changes of api endpoints

Changes:

• introduce OptionsSnapshot
  • support greeks and "implied_volatility" of options snapshot
• support filter parameters of options chain api endpoint
  • ref. https://docs.alpaca.markets/reference/optionchain

[gnvk]

LGTM. Thanks @hiohiohio !

[impredicative]

@hiohiohio "greeks": "greeks" doesn't look right. It's mapping to itself.

[hiohiohio]

@impredicative thank you for the comment.
Yeah, it looks a confusing but. We are using this SNAPSHOT_MAPPING in the below [1] to create mapped_snapshot dict to convert raw_data dict into an object. Since we do not pass raw_data into an initializer of an object but mapped_snapshot only, we need to map required fields into mapped_snapshot dict.

*1

alpaca-py/alpaca/data/models/snapshots.py

Lines 122 to 126 in eae556d

	mapped_snapshot = {
	SNAPSHOT_MAPPING.get(key): val
	for key, val in raw_data.items()
	if key in SNAPSHOT_MAPPING
	}