store pubkey on its own table

[pikonha]

Feature Request

Since ENS doesn't have the concept of reserved keys on the texts table, we need to decouple the pubkey from the texts table.

Describe Preferred Solution

• Create a pubkey table
• Remove the pubkey reserved key from the texts database
• Redirect setPubkey calls to the newly created table

QA Replication steps

1. Create a 2LD (e.g techno.eth)
2. Set its resolver to be the database resolver
3. Set a pubkey record through the PubkeyResolver interface:

function setPubkey(
    bytes32 node,
    bytes32 x,
    bytes32 y
) external virtual authorised(node)

4. Check whether this record is being correctly fetched