feat(subscription/l2Book): add optional 'fast' field

[vtx100]

What & why

Add the optional 'fast' field in the websocket subscription schema of L2BookRequest.
The field changes the manner in which the responses are pushed("5 levels if fast, 20 levels if slow")->docs (search for l2Book)
Via telegram Hyperliquid API Announcements(@hyperliquid_api) :

• "l2Book subscriptions will include an optional fast: true field. When set, the book will push 5 levels every 0.5 seconds The subscription without the flag will push 20 levels every 5 seconds" (https://t.me/hyperliquid_api/326).
• This was however change to based on feedback: "l2Book without fast: true will push 20 levels every 2 seconds, instead of every 5 seconds"(https://t.me/hyperliquid_api/327)

Type of change

• Bug fix
• New API method / feature
• Schema/type update to match the Hyperliquid API
• Breaking change

[gambinish]

Is there anything we can do to help move this forward? We are building on top of this and are keen to adopt the fast: true flag into our order book UI as there are a few other SDKs that already support this.

Let us know if there's anything we can do to get this over the finish line!

[nktkas]

I pushed a few changes on top before merging:

• Added fast to L2BookEvent
• Reworked the request field to v.optional(v.boolean())
• Fixed the field JSDoc

Thanks for your contribution!

[nktkas]

@gambinish, I was planning to ship the release within 1-2 days (I need to write up all the changes in the new version + double-check that the current API schemas/types are still accurate).

[gambinish]

@gambinish, I was planning to ship the release within 1-2 days (I need to write up all the changes in the new version + double-check that the current API schemas/types are still accurate).

Thank you! We're going to go ahead and integrate this now. Appreciate your effort here.