Automatically get float label type in most cases

[water111]

It doesn't work if a constant float is used directly in a function argument.

[coveralls]

Pull Request Test Coverage Report for Build 833797229

• 8 of 22 (36.36%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.01%) to 69.212%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
decompiler/ObjectFile/ObjectFileDB.cpp	0	1	0.0%
decompiler/config.cpp	0	2	0.0%
test/offline/offline_test_main.cpp	0	2	0.0%
decompiler/IR2/AtomicOpForm.cpp	4	8	50.0%
common/util/json_util.cpp	3	8	37.5%

Totals
Change from base Build 833686994:	-0.01%
Covered Lines:	34271
Relevant Lines:	49516

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💛 - Coveralls