refactor: Add simple clang-tidy readability checks (#6556)

This change enables the following clang-tidy checks:
-  readability-avoid-nested-conditional-operator,
-  readability-avoid-return-with-void-value,
-  readability-braces-around-statements,
-  readability-const-return-type,
-  readability-container-contains,
-  readability-container-size-empty,
-  readability-else-after-return,
-  readability-make-member-function-const,
-  readability-redundant-casting,
-  readability-redundant-inline-specifier,
-  readability-redundant-member-init,
-  readability-redundant-string-init,
-  readability-reference-to-constructed-temporary,
-  readability-static-definition

src/test/basics/Number_test.cpp

@@ -199,9 +199,13 @@ public:
             }
         };
         if (scale == MantissaRange::small)
+        {
             test(cSmall);
+        }
         else
+        {
             test(cLarge);
+        }
         {
             bool caught = false;
             try
@@ -291,9 +295,13 @@ public:
             }
         };
         if (scale == MantissaRange::small)
+        {
             test(cSmall);
+        }
         else
+        {
             test(cLarge);
+        }
     }
 
     void
@@ -314,9 +322,13 @@ public:
         };
         auto tests = [&](auto const& cSmall, auto const& cLarge) {
             if (scale == MantissaRange::small)
+            {
                 test(cSmall);
+            }
             else
+            {
                 test(cLarge);
+            }
         };
         auto const maxMantissa = Number::maxMantissa();
 
@@ -622,9 +634,13 @@ public:
         auto const maxMantissa = Number::maxMantissa();
         auto tests = [&](auto const& cSmall, auto const& cLarge) {
             if (scale == MantissaRange::small)
+            {
                 test(cSmall);
+            }
             else
+            {
                 test(cLarge);
+            }
         };
         saveNumberRoundMode save{Number::setround(Number::to_nearest)};
         {