Add the STR RPC to overlord and game code

[water111]

The STR RPC is used to load animation and game text. It requires adding an additional RPC thread to OVERLORD, and support for it in GOAL. Most of the complicated stuff on the IOP side is already done for the other RPCs, so this is mostly adding support on the GOAL side.

[coveralls]

Pull Request Test Coverage Report for Build 377597579

• 58 of 108 (53.7%) changed or added relevant lines in 10 files are covered.
• 79 unchanged lines in 6 files lost coverage.
• Overall coverage decreased (-0.5%) to 80.865%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
game/overlord/iso.cpp	9	10	90.0%
common/util/FileUtil.cpp	3	5	60.0%
game/overlord/iso_api.cpp	4	18	22.22%
game/overlord/stream.cpp	21	54	38.89%

Files with Coverage Reduction	New Missed Lines	%
game/kernel/klink.cpp	1	74.63%
game/kernel/kmalloc.cpp	1	46.58%
game/overlord/isocommon.cpp	3	30.68%
game/kernel/kscheme.cpp	18	64.23%
game/kernel/fileio.cpp	21	54.36%
game/sce/sif_ee.cpp	35	50.5%

Totals
Change from base Build 377574893:	-0.5%
Covered Lines:	16629
Relevant Lines:	20564

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💛 - Coveralls