String obfuscation hides string literals from static analysis but
requires string literals be used inside protected functions.
- Enable string obfuscation for all function groups.
- Change some global `std::string` to `const char[]` to ensure that
the `std::string` is constructed inside a protected function so
that string obfuscation correctly applies to the string literal.
Bug: 270566889
Merged from https://widevine-internal-review.googlesource.com/168485
Merge conflicts were caused by formating changes. Resolved by taking
the newer version.
Merged from https://widevine-internal-review.googlesource.com/169511
Change-Id: Ie7f3e94f89671a34e4792efa174f96a17d713f9e
17a1de8d2d