Logrus hooks for terminal vs log-file output (#16102)

## Review after #16059 

**What type of PR is this?**
Feature

**What does this PR do?**
This PR introduces logrus writer hooks into the logging of prysm.
when log-format is text:
- set the default logrus output to be `io.Discard`
- create a writer hook for terminal, with formatting and coloring
enabled.
- create a separate writer hook for log-file (if enabled), without
coloring.

This immediately allows for having formatted/colored terminal logs,
while keeping the log-file clean.

changelog/bastin_logrus-hooks-add.md

@@ -0,0 +1,4 @@
+### Added
+
+- Added separate logrus hooks for handling the formatting and output of terminal logs vs log-file logs, instead of the
+  default logrus output.