core/api-spec: add "type" filter to /list-access-tokens
core/api-spec: add "type" filter to /list-access-tokens

This commit proposes to add the ability to filter access tokens
by their type. The filter will be used by the dashboard to ensure
that client tokens exist before the require-client-token restriction
is enabled.

Closes chain/chainprv#1932

chain/chain,chain/chain,chain/chain,chain/chain,chain/chain,chain/chain