1. Use `std::is_standard_layout` and `std::is_trivially_copyable` instead of `std::is_pod` for KV byte-wise serialization, which fixes compile issue for Boost UUIDs
2. Use `std::has_unique_object_representations` instead of `alignof(T) == 1` for epee byte spans and epee hex functions
3. Removed reimplementation of `std::hash` for `boost::uuids::uuid
4. Removed `<<` operator overload for `crypto::secret_key`
5. Removed instances in code where private view key was dumped to the log in plaintext
a46b6ba contrib: add more valgrind suppressions for spurious issues (moneromooo-monero)
7f3e31d unit_tests: fix accessing invalid memory in tree_hash test (moneromooo-monero)
- Performance improvements
- Added `span` for zero-copy pointer+length arguments
- Added `std::ostream` overload for direct writing to output buffers
- Removal of unused `string_tools::buff_to_hex`
