applet.jtag_mips: reset Rocc before entering probe mode. Otherwise all our writes will just get ignored. This commit also adds detection of unexpected core reset.

arch.mips.ejtag: fix definition of DR_IMPCODE.

applet.jtag: pulse TRST# and reset TAPs when run. Almost all circumstances make this sensible. The rare applet that needs to, specifically, not reset the test chain when run, can opt out of this explicitly. Before this commit, the jtag-mips applet would crash at startup.

applet.jtag: enumerate-ir: fix endianness.

applet.jtag: fix misdetection of 32-bit DRs at end of chain as truncated.

applet.jtag_pinout: improve messages related to detection of TRST#.

applet.jtag_pinout: fix failure to detect TRST# on pin 0.

applet.jtag_pinout: fix type confusion between bit and pin numbers. Before this commit, the applet would break if the JTAG pin set would not start with pin 0.

applet.jtag_pinout: never try to detect TRST# with 4 only pins.

protocol.vgm: add missing VGMStreamPlayer stub.