[clang-tidy] Check request: performance-construct-regex-only-once

[denzor200]

Construction time of a std::regex variable might be a bottleneck.
Thus we should never declare it as non-static block-scope variable in order to variable gets initialised only once.

std::regex r1("(.*)");            // OK
static std::regex r2("(.*)");     // OK
void process() {
    std::regex r3("(.*)");        // INCORRECT
    static std::regex r4("(.*)"); // OK
}