util: Move util/string.h functions to util namespace

There are no changes to behavior. Changes in this commit are all additions, and
are easiest to review using "git diff -U0 --word-diff-regex=." options.

Motivation for this change is to keep util functions with really generic names
like "Split" and "Join" out of the global namespace so it is easier to see
where these functions are defined, and so they don't interfere with function
overloading, especially since the util library is a dependency of the kernel
library and intended to be used with external code.

Author: ryanofsky

src/base58.cpp

@@ -14,6 +14,8 @@
 
 #include <limits>
 
+using util::ContainsNoNUL;
+
 /** All alphanumeric characters except for "0", "I", "O", and "l" */
 static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
 static const int8_t mapBase58[256] = {

src/bench/bench.cpp

@@ -18,6 +18,7 @@
 #include <vector>
 
 using namespace std::chrono_literals;
+using util::Join;
 
 const std::function<void(const std::string&)> G_TEST_LOG_FUN{};
 

src/bench/bench_bitcoin.cpp

@@ -16,6 +16,8 @@
 #include <sstream>
 #include <vector>
 
+using util::SplitString;
+
 static const char* DEFAULT_BENCH_FILTER = ".*";
 static constexpr int64_t DEFAULT_MIN_TIME_MS{10};
 /** Priority level default value, run "all" priority levels */

src/bitcoin-cli.cpp

@@ -42,6 +42,9 @@
 #include <event2/keyvalq_struct.h>
 #include <support/events.h>
 
+using util::Join;
+using util::ToString;
+
 // The server returns time values from a mockable system clock, but it is not
 // trivial to get the mocked time from the server, nor is it needed for now, so
 // just use a plain system_clock.

src/bitcoin-tx.cpp

@@ -32,6 +32,11 @@
 #include <functional>
 #include <memory>
 
+using util::SplitString;
+using util::ToString;
+using util::TrimString;
+using util::TrimStringView;
+
 static bool fCreateBlank;
 static std::map<std::string,UniValue> registers;
 static const int CONTINUE_EXECUTION=-1;

src/bitcoin-wallet.cpp

@@ -24,6 +24,8 @@
 #include <string>
 #include <tuple>
 
+using util::Join;
+
 const std::function<std::string(const char*)> G_TRANSLATION_FUN = nullptr;
 
 static void SetupWalletToolArgs(ArgsManager& argsman)

src/blockfilter.cpp

@@ -16,6 +16,8 @@
 #include <util/golombrice.h>
 #include <util/string.h>
 
+using util::Join;
+
 static const std::map<BlockFilterType, std::string> g_filter_types = {
     {BlockFilterType::BASIC, "basic"},
 };

src/chainparams.cpp

@@ -21,6 +21,8 @@
 #include <stdexcept>
 #include <vector>
 
+using util::SplitString;
+
 void ReadSigNetArgs(const ArgsManager& args, CChainParams::SigNetOptions& options)
 {
     if (args.IsArgSet("-signetseednode")) {

src/clientversion.cpp

@@ -13,6 +13,8 @@
 #include <string>
 #include <vector>
 
+using util::Join;
+
 /**
  * Name of client reported in the 'version' message. Report the same name
  * for both bitcoind and bitcoin-qt, to make it harder for attackers to

src/common/config.cpp

@@ -27,6 +27,9 @@
 #include <utility>
 #include <vector>
 
+using util::TrimString;
+using util::TrimStringView;
+
 static bool GetConfigOptions(std::istream& stream, const std::string& filepath, std::string& error, std::vector<std::pair<std::string, std::string>>& options, std::list<SectionInfo>& sections)
 {
     std::string str, prefix;