Get spec params.

Retrieve specification configuration used on this node. The configuration should include:

• Constants for all hard forks known by the beacon node, for example the phase 0 and altair values
• Presets for all hard forks supplied to the beacon node, for example the phase 0 and altair values
• Configuration for the beacon node, for example the mainnet values

Values are returned with following format:

• any value starting with 0x in the spec is returned as a hex string
• numeric values are returned as a quoted integer