Replace boost::optional with std::optional (#4877)

src/controllers/userdata/UserData.hpp

@@ -3,11 +3,12 @@
 #include "util/RapidjsonHelpers.hpp"
 #include "util/RapidJsonSerializeQString.hpp"
 
-#include <boost/optional.hpp>
 #include <pajlada/serialize.hpp>
 #include <QColor>
 #include <QString>
 
+#include <optional>
+
 namespace chatterino {
 
 // UserData defines a set of data that is defined for a unique user
@@ -15,7 +16,7 @@ namespace chatterino {
 // or a user note that should be displayed with the user
 // Replacement fields should be optional, where none denotes that the field should not be updated for the user
 struct UserData {
-    boost::optional<QColor> color{boost::none};
+    std::optional<QColor> color{std::nullopt};
 
     // TODO: User note?
 };

src/controllers/userdata/UserDataController.cpp

@@ -2,6 +2,7 @@
 
 #include "singletons/Paths.hpp"
 #include "util/CombinePath.hpp"
+#include "util/Helpers.hpp"
 
 namespace {
 
@@ -42,15 +43,14 @@ void UserDataController::save()
     this->sm->save();
 }
 
-boost::optional<UserData> UserDataController::getUser(
-    const QString &userID) const
+std::optional<UserData> UserDataController::getUser(const QString &userID) const
 {
     std::shared_lock lock(this->usersMutex);
     auto it = this->users.find(userID);
 
     if (it == this->users.end())
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return it->second;
@@ -67,8 +67,8 @@ void UserDataController::setUserColor(const QString &userID,
 {
     auto c = this->getUsers();
     auto it = c.find(userID);
-    boost::optional<QColor> finalColor =
-        boost::make_optional(!colorString.isEmpty(), QColor(colorString));
+    std::optional<QColor> finalColor =
+        makeConditionedOptional(!colorString.isEmpty(), QColor(colorString));
     if (it == c.end())
     {
         if (!finalColor)

src/controllers/userdata/UserDataController.hpp

@@ -7,11 +7,11 @@
 #include "util/RapidJsonSerializeQString.hpp"
 #include "util/serialize/Container.hpp"
 
-#include <boost/optional.hpp>
 #include <pajlada/settings.hpp>
 #include <QColor>
 #include <QString>
 
+#include <optional>
 #include <shared_mutex>
 #include <unordered_map>
 
@@ -22,7 +22,7 @@ class IUserDataController
 public:
     virtual ~IUserDataController() = default;
 
-    virtual boost::optional<UserData> getUser(const QString &userID) const = 0;
+    virtual std::optional<UserData> getUser(const QString &userID) const = 0;
 
     virtual void setUserColor(const QString &userID,
                               const QString &colorString) = 0;
@@ -35,7 +35,7 @@ public:
 
     // Get extra data about a user
     // If the user does not have any extra data, return none
-    boost::optional<UserData> getUser(const QString &userID) const override;
+    std::optional<UserData> getUser(const QString &userID) const override;
 
     // Update or insert extra data for the user's color override
     void setUserColor(const QString &userID,