server: logs - unified format and --log-format option (#5700)

* server: logs - always use JSON logger, add add thread_id in message, log task_id and slot_id

* server : skip GH copilot requests from logging

* server : change message format of server_log()

* server : no need to repeat log in comment

* server : log style consistency

* server : fix compile warning

* server : fix tests regex patterns on M2 Ultra

* server: logs: PR feedback on log level

* server: logs: allow to choose log format in json or plain text

* server: tests: output server logs in text

* server: logs switch init logs to server logs macro

* server: logs ensure value json value does not raised error

* server: logs reduce level VERBOSE to VERB to max 4 chars

* server: logs lower case as other log messages

* server: logs avoid static in general

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* server: logs PR feedback: change text log format to: LEVEL [function_name] message | additional=data

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

Author: phymbert

examples/server/README.md

@@ -39,10 +39,12 @@ see https://github.com/ggerganov/llama.cpp/issues/1437
 - `--mmproj MMPROJ_FILE`: Path to a multimodal projector file for LLaVA.
 - `--grp-attn-n`: Set the group attention factor to extend context size through self-extend(default: 1=disabled), used together with group attention width `--grp-attn-w`
 - `--grp-attn-w`: Set the group attention width to extend context size through self-extend(default: 512), used together with group attention factor `--grp-attn-n`
-- `-n, --n-predict`: Set the maximum tokens to predict (default: -1)
+- `-n N, --n-predict N`: Set the maximum tokens to predict (default: -1)
 - `--slots-endpoint-disable`: To disable slots state monitoring endpoint. Slots state may contain user data, prompts included.
 - `--metrics`: enable prometheus `/metrics` compatible endpoint (default: disabled)
 - `--chat-template JINJA_TEMPLATE`: Set custom jinja chat template. This parameter accepts a string, not a file name (default: template taken from model's metadata). We only support [some pre-defined templates](https://github.com/ggerganov/llama.cpp/wiki/Templates-supported-by-llama_chat_apply_template)
+- `--log-disable`: Output logs to stdout only, default: enabled.
+- `--log-format FORMAT`: Define the log output to FORMAT: json or text (default: json)
 
 ## Build