Merge #20530: lint, refactor: Update cppcheck linter to c++17 and imp…

<pre>Merge #20530: lint, refactor: Update cppcheck linter to c++17 and improve explicit usage 1e62350ca20898189904a88dfef9ea11ddcd8626 refactor: Improve use of explicit keyword (Fabian Jahr) c502a6dbfb854ca827a5a3925394f9e09d29b898 lint: Use c++17 std in cppcheck linter (Fabian Jahr) Pull request description: I found the `extended-lint-cppcheck` linter still uses `std=c++11` when reviewing #20471. The only difference in the output after this change is one line is missing: ``` src/script/descriptor.cpp:159:5: warning: Struct 'PubkeyProvider' has a constructor with 1 argument that is not explicit. [noExplicitConstructor] ``` After some digging, I am still not sure why this one is ignored with c++17 when 40 other`noExplicitConstructor` warnings were still appearing. In the second commit, I fix these warnings, adding `explicit` where appropriate and adding fixes to ignore otherwise. ACKs for top commit: practicalswift: cr ACK 1e62350ca20898189904a88dfef9ea11ddcd8626: patch looks correct! MarcoFalke: review ACK 1e62350ca20898189904a88dfef9ea11ddcd8626 Tree-SHA512: dff7b324429a57160e217cf38d9ddbb6e70c6cb3d3e3e0bd4013d88e07afc2292c3df94d0acf7122e9d486322821682ecf15c8f2724a78667764c05d47f89a12</pre>

Merge #20222: refactor: CTxMempool constructor clean up

<pre>Merge #20222: refactor: CTxMempool constructor clean up f15e780b9e57554c723bc02aa41150ecf3e3a8c9 refactor: Clean up CTxMemPool initializer list (Elle Mouton) e3310692d0e9720e960b9785274ce1f0b58b4cd7 refactor: Make CTxMemPool::m_check_ratio a const and a constructor argument (Elle Mouton) 9d4b4b2c2c49774523de740d6492ee5b1ee15e74 refactor: Avoid double to int cast for nCheckFrequency (Elle Mouton) Pull request description: This PR cleans up the CTxMemPool interface by including the ratio used to determine when a mempool sanity check should run in the constructor of CTxMempool instead of using nCheckFrequency which required a cast from a double to a uint32_t. Since nCheckFrequency (now called m_check_ratio) is set in the constructor and only every read from there after, it can be turned into a const and no longer needs to be guarded by the 'cs' lock. Since nCheckFrequency/m_check_ratio no longer needs to lock the 'cs' mutux, mutex lock line in the "CTxMempool::check" function can be moved below where the m_check_ratio variable is checked. Since the variable is 0 by default (meaning that "CTxMempool::check" will most likely not run its logic) this saves us from unnecessarily grabbing the lock. ACKs for top commit: jnewbery: utACK f15e780b9e57554c723bc02aa41150ecf3e3a8c9 MarcoFalke: ACK f15e780b9e57554c723bc02aa41150ecf3e3a8c9 &#128088; glozow: utACK theStack: Code Review ACK f15e780b9e57554c723bc02aa41150ecf3e3a8c9 Tree-SHA512: d83f3b5311ca128847b621e5e999c7e1bf0f4e6261d4cc090fb13e229a0f7eecd66ad997f654f50a838baf708d1515740aa3bffc244909a001d01fd5ae398b68</pre>