Logs: separate new head infos event with different verbosity

Context

now that !7603 (merged) is merged we can proceed cleaning up stdout

fixes #4581 (closed)

This MR set separates events advertizing of new heads in two parts with different level of verbosity:

• branch_switch, head_increment and ignore_head are stripped from timestamp and fitness and kept at level Notice
• a new event head_infos, of level Info contains the fitness and the timestamp

Only the hash and the level are kept. The formatting is also changed to stay on one line. Hence User logs are changed in the following way:

Before

Feb 13 18:37:59.487 - validator.chain: Update current head to BLktX5fQNXbCvGV1UkHeszKhjQUUQRCXeXCadgsUHtL8jNYP6HE
Feb 13 18:37:59.487 - validator.chain:   (level 676530, timestamp 2023-02-13T17:37:50-00:00, fitness
Feb 13 18:37:59.487 - validator.chain:   02::000a52b2::::ffffffff::00000000), same branch

After

Feb 13 18:31:05.538 - validator.chain: head is now BMHTe7MRFUks7dTbs3cfXpwu58gxuKEEHExLj6xjwL1oYHP8fZ3 (676503)

and Internal logs now have the following shape:

2023-02-13T17:34:35.700-00:00 [validator.chain.head_increment] head is now BLi1enjMNjRKj5hHm8U2ortppnUZX
9QdKWfqpV93SzPdZyMtUt3 (676517)
2023-02-13T17:34:35.700-00:00 [validator.chain.head_infos] treated block has timestamp 2023-02-13T17:3
4:35-00:00 with fitness 02::000a52a5::::ffffffff::00000000)

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
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