[datalog] Move all DataLog functionality to new datalog library (#7641)

Currently the major DataLog backend API (reading and writing) is split between wpiutil and glass. In the interest of allowing code that wants to use these APIs to not need to link to glass and declutter wpiutil, all of those APIs are moved to a new library named "datalog".

Signed-off-by: Jade Turner <spacey-sooty@proton.me>
Co-authored-by: Jade Turner <spacey-sooty@proton.me>
Co-authored-by: Gold856 <117957790+Gold856@users.noreply.github.com>

datalog/src/test/native/cpp/FileLoggerTest.cpp

@@ -0,0 +1,59 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "wpi/datalog/FileLogger.h"
+
+TEST(FileLoggerTest, BufferSingleLine) {
+  std::vector<std::string> buf;
+  auto func = wpi::log::FileLogger::Buffer(
+      [&buf](std::string_view line) { buf.emplace_back(line); });
+  func("qwertyuiop\n");
+  EXPECT_EQ("qwertyuiop", buf[0]);
+}
+
+TEST(FileLoggerTest, BufferMultiLine) {
+  std::vector<std::string> buf;
+  auto func = wpi::log::FileLogger::Buffer(
+      [&buf](std::string_view line) { buf.emplace_back(line); });
+  func("line 1\nline 2\nline 3\n");
+  EXPECT_EQ("line 1\nline 2\nline 3", buf[0]);
+}
+
+TEST(FileLoggerTest, BufferPartials) {
+  std::vector<std::string> buf;
+  auto func = wpi::log::FileLogger::Buffer(
+      [&buf](std::string_view line) { buf.emplace_back(line); });
+  func("part 1");
+  func("part 2\npart 3");
+  EXPECT_EQ("part 1part 2", buf[0]);
+  func("\n");
+  EXPECT_EQ("part 3", buf[1]);
+}
+
+TEST(FileLoggerTest, BufferMultiplePartials) {
+  std::vector<std::string> buf;
+  auto func = wpi::log::FileLogger::Buffer(
+      [&buf](std::string_view line) { buf.emplace_back(line); });
+  func("part 1");
+  func("part 2");
+  func("part 3");
+  func("part 4\n");
+  EXPECT_EQ("part 1part 2part 3part 4", buf[0]);
+}
+TEST(FileLoggerTest, BufferMultipleMultiLinePartials) {
+  std::vector<std::string> buf;
+  auto func = wpi::log::FileLogger::Buffer(
+      [&buf](std::string_view line) { buf.emplace_back(line); });
+  func("part 1");
+  func("part 2\npart 3");
+  func("part 4\n");
+  EXPECT_EQ("part 1part 2", buf[0]);
+  EXPECT_EQ("part 3part 4", buf[1]);
+}