Create an authorizer example

[bbenligiray]

We can create an example in airnode-examples for implementing a custom authorizer and demonstrate its usage, similar to the relay security scheme example

[dcroote]

For anyone coming across this issue, the coingecko-cross-chain-authorizer airnode-examples integration, introduced in #1488 and planned to be released as part of Airnode v0.10, demonstrates how very basic same-chain and cross-chain authorizer contracts can be used together to authorize requests.

Leaving the task open as there is still an opportunity to demonstrate more complex authorizer contract logic.

[dcroote]

Closing for the same reason as #1555: RequesterAuthorizerWithAirnode is unused and has been superceded. See #1722 and https://api3workspace.slack.com/archives/C02AYRX8D89/p1680698758234279

[dcroote]

Changing to "Closing as not planned"