Add a strict and a permissive decoder, allow different reserved alphabets

CMakeLists.txt

Makefile

build.yaml

src/core/lib/support/percent_encoding.c

src/core/lib/support/percent_encoding.h

test/core/support/percent_decode_fuzzer.c

test/core/support/percent_encode_fuzzer.c

test/core/support/percent_encoding_test.c

tools/codegen/core/gen_percent_encoding_tables.c

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

vsprojects/buildtests_c.sln

vsprojects/grpc.sln

...rcent_encoding_tables/gen_percent_encoding_tables.vcxproj

...coding_tables/gen_percent_encoding_tables.vcxproj.filters