Refactor `gui/journal` text editor to dedicated `TextArea` widget #5144

Job	Run time
lint / lint	15s
docs / Build linux64	1m 6s
test / Windows MSVC / Build win64	17m 38s
test / Linux gcc-12 / Build linux64	6m 37s
test / Linux gcc-10 / Build linux64	4m 49s
test / Run Linux test suite / Test (ubuntu, gcc-10, default plugins, default config)	33s
test / Run Linux test suite (gcc-12, all plugins) / Test (ubuntu, gcc-12, all plugins, default config)	37s
test / Run Windows test suite / Test (windows, msvc, default plugins, default config)	52s
test / Run Windows test suite (empty config) / Test (windows, msvc, default plugins, empty config)	51s
	33m 18s

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