[Impeller] Apply the Windows friendly path solution for remaining ImpellerC paths

[bdero]

Fixes new engine build issues I'm running into on Windows today:

[6880/7798] ACTION //flutter/lib/ui/fixtures/shaders/suppo...pile_supported_op_shaders(//build/toolchain/win:clang_x64)
FAILED: gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/145_OpMatrixTimesVector.frag.iplr
C:/Users/bdero/.vpython-root/cf506f/Scripts/python.exe ../../build/gn_run_binary.py impellerc.exe --input=../../flutter/lib/ui/fixtures/shaders/supported_op_shaders/145_OpMatrixTimesVector.frag --include=../../flutter/lib/ui/fixtures/shaders/supported_op_shaders --include=C:/Users/bdero/projects/flutter/engine/src/flutter/impeller/compiler/shader_lib --depfile=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/145_OpMatrixTimesVector.frag.d --sksl --sl=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/145_OpMatrixTimesVector.frag.iplr --spirv=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/145_OpMatrixTimesVector.frag.spirv --iplr
Could not figure out working directory.
Invalid flags specified.

ImpellerC is an offline shader processor and reflection engine.
---------------------------------------------------------------
Valid Argument are:
One of [ --metal-desktop --metal-ios --opengl-desktop --opengl-es --runtime-stage-gles --runtime-stage-metal --sksl --vulkan ]
--input=<glsl_file>
[optional] --input-kind={comp, frag, tesc, tese, vert, }
--sl=<sl_output_file>
--spirv=<spirv_output_file>
[optional] --iplr (causes --sl file to be emitted in iplr format)
[optional] --reflection-json=<reflection_json_file>
[optional] --reflection-header=<reflection_header_file>
[optional] --reflection-cc=<reflection_cc_file>
[optional,multiple] --include=<include_directory>
[optional,multiple] --define=<define>
[optional] --depfile=<depfile_path>
[optional] --json

[6881/7798] ACTION //flutter/lib/ui/fixtures/shaders/suppo...pile_supported_op_shaders(//build/toolchain/win:clang_x64)
FAILED: gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/167_OpLogicalAnd.frag.iplr
C:/Users/bdero/.vpython-root/cf506f/Scripts/python.exe ../../build/gn_run_binary.py impellerc.exe --input=../../flutter/lib/ui/fixtures/shaders/supported_op_shaders/167_OpLogicalAnd.frag --include=../../flutter/lib/ui/fixtures/shaders/supported_op_shaders --include=C:/Users/bdero/projects/flutter/engine/src/flutter/impeller/compiler/shader_lib --depfile=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/167_OpLogicalAnd.frag.d --sksl --sl=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/167_OpLogicalAnd.frag.iplr --spirv=gen/flutter/lib/ui/fixtures/shaders/supported_op_shaders/iplr/167_OpLogicalAnd.frag.spirv --iplr
Could not figure out working directory.
Invalid flags specified.

ImpellerC is an offline shader processor and reflection engine.
---------------------------------------------------------------
Valid Argument are:
One of [ --metal-desktop --metal-ios --opengl-desktop --opengl-es --runtime-stage-gles --runtime-stage-metal --sksl --vulkan ]
--input=<glsl_file>
[optional] --input-kind={comp, frag, tesc, tese, vert, }
--sl=<sl_output_file>
--spirv=<spirv_output_file>
[optional] --iplr (causes --sl file to be emitted in iplr format)
[optional] --reflection-json=<reflection_json_file>
[optional] --reflection-header=<reflection_header_file>
[optional] --reflection-cc=<reflection_cc_file>
[optional,multiple] --include=<include_directory>
[optional,multiple] --define=<define>
[optional] --depfile=<depfile_path>
[optional] --json

[7744/7798] STAMP obj/flutter/tools/font-subset/font-subset.stamp
ninja: build stopped: cannot make progress due to previous errors.

Replacing the working directory path alone works for the above, but I went ahead and just replaced the couple of other remaining paths/deleted the non-working utils.

[flutter-dashboard]

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If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

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