Fixes warnings like:
```
dolphin/Source/UnitTests/Common/BitUtilsTest.cpp:5:
../Externals/gtest/googletest/include/gtest/gtest.h:1392:11: warning: comparison of integers of different signs: 'const unsigned long' and 'const int' [-Wsign-compare]
if (lhs == rhs) {
~~~ ^ ~~~
../Externals/gtest/googletest/include/gtest/gtest.h:1421:12: note: in instantiation of function template specialization 'testing::internal::CmpHelperEQ<unsigned long, int>' requested here
return CmpHelperEQ(lhs_expression, rhs_expression, lhs, rhs);
^
dolphin/Source/UnitTests/Common/BitUtilsTest.cpp:12:3: note: in instantiation of function template specialization 'testing::internal::EqHelper<false>::Compare<unsigned long, int>' requested here
EXPECT_EQ(Common::BitSize<s8>(), 8);
^
../Externals/gtest/googletest/include/gtest/gtest.h:1924:63: note: expanded from macro 'EXPECT_EQ'
EqHelper<GTEST_IS_NULL_LITERAL_(val1)>::Compare, \
```
This attempts to make some bit arithmetic more self-documenting and also
make it easier during review to identify potential off-by-one errors by
making it possible to just specify which bits are being extracted.
Functions both support the case where bits being extracted can vary and
fixed bit extraction. In the case the bits are fixed, compile-time asserts
are present to prevent accidental API usage at compile-time.
e.g. Instead of shifting and masking to get bits 10 to 15,
Common::ExtractBits<10, 15>(value) can just be done instead.
Michael Maltese