This PR is part of a couple of rewrites to be carried out normalising
the cases where we have constant declaration. In this PR we have the
following fixes:
- Remove redundant `const` qualifier alongside `constexpr`
- Function-scope constants as `static constexpr`
- Remove the use of `extern` declarations
- Whenever possible use `constexpr`
- When appropriate, use `MakeFixedFlatSet`.
These changes are in conformance with some upcoming clarified guidelines.
Furthermore, this takes us one step closer to have some automation for
clang-tidy, as right now there are too many clang-tidy warnings around
constant/variable naming.
Resolves https://github.com/brave/brave-browser/issues/42490
cdesouza-chromium
f6fdd59e5b