Encode `LogMsg` using protobuf #15122

Job	Run time
paths-filter	7s
Checks / Rerun lints	33s
Checks / Check if running codegen would produce any changes	1m 13s
Checks / Lint markdown	23s
Checks / Spell Check	8s
Checks / Misc formatting	23s
Checks / markdown-paths-filter	4s
Checks / Check links	28s
C++ tests / C++ formatting check	1m 14s
C++ tests / matrix_prep	5s
Minimum CLI Build / Set Config (linux-x64)	2s
Python Checks / Python lints (ruff, mypy, …)	33s
Python Checks / Test Python Docs	24s
Rust Checks / Rust lints (fmt, check, clippy, tests, doc)	1m 19s
Build rerun_js / Build rerun_js	1m 18s
Rust Checks / Test on ${{ matrix.name }}	0s
Build web viewer / Build web viewer	1m 17s
Deploy Landing Preview / Deploy	51s
Minimum CLI Build / Build rerun-cli (ubuntu-latest-16-cores)	1s
C++ tests / C++ build & test - Linux x64, C++17	1s
C++ tests / C++ build & test - Linux x64, C++20	1s
C++ tests / C++ build & test - Windows x64	54s
C++ tests / C++ build & test - Mac aarch64	54s
Minimum Wheel Build	0s
Minimum Wheel Test	0s
Upload Web	0s
	12m 13s

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