UCS/LOG: Print multi-line logs in a single operation

[guy-ealey-morag]

What?

Print multi-line logs in a single operation to avoid other logs from being interleaved between them, and improve logging efficiency.

Why?

This is done to avoid any other logs from interleaving between multi-line logs, which until now were printed one-by-one.

How?

Every log is tested for \n, if it has at least one then it's printed with the multi-line logic, otherwise it's printed using the existing logic (the separation allows more efficient handling of the single line case).

Also, added detection for logs that don't require formatting (ones that use "%s" as their format string), in this case the argument is used as-is and there is no need to spend time and resources on formatting them.
This allows printing buffers that are larger than what ucs_alloca() allows.
Notice that this approach required removing the use of strtok_r because it is modifying the given string.

[guy-ealey-morag]

@iyastreb @brminich
I updated the multi-line printing logic to allocate 2048 bytes on the stack, and to use snprintf directly instead of string buffers.
When the log is too long, is it truncated to 2048 characters ending with > to indicate the truncation.

[guy-ealey-morag]

I refactored the code to have a single printing logic that is reused for single line and multi line logs (UCS_LOG_PRINTF macro)

[guy-ealey-morag]

A complete solution to this issue will be using write or writev with the downside of using more system calls compared to printf (perf testing showed logging time can double when using write over printf)

Closing until it's prioritized again