[decompiler] support break

[water111]

Currently as a begin ending with a goto.

[coveralls]

Pull Request Test Coverage Report for Build 869709564

• 106 of 169 (62.72%) changed or added relevant lines in 8 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.2%) to 69.748%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
decompiler/IR2/FormExpressionAnalysis.cpp	25	29	86.21%
decompiler/analysis/cfg_builder.cpp	29	35	82.86%
decompiler/ObjectFile/ObjectFileDB_IR2.cpp	0	8	0.0%
decompiler/IR2/Form.cpp	27	49	55.1%
decompiler/Function/CfgVtx.cpp	9	32	28.13%

Files with Coverage Reduction	New Missed Lines	%
decompiler/ObjectFile/ObjectFileDB_IR2.cpp	1	0%

Totals
Change from base Build 869435161:	0.2%
Covered Lines:	35840
Relevant Lines:	51385

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💛 - Coveralls

[water111]

• Add some features to CfgVtx.cpp to support getting the destination of a break as a block index and figuring out which blocks need labels
• Add labels as needed in cfg_builder based on the data from CfgVtx.cpp
• Fix a bug where accessing a bitfield with a single right shift would give int in the decompiler always
• Convert a break into code + a goto. I think in all cases random goto forwards end up turning into breaks, so trying to convert these into some block-like structure isn't always possible.
• Recognize converting a symbol into a string.
• Don't crash on failed stack spills
• Clean up dead code in a break like we did for return
• Decompile method 19 of res-lump. This now can be copy-pasted from the decompiler!