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/app/PayStrand_test.cpp

@@ -183,8 +183,10 @@ class ElementComboIter
     hasAny(std::initializer_list<SB> sb) const
     {
         for (auto const s : sb)
+        {
             if (has(s))
                 return true;
+        }
         return false;
     }
 
@@ -194,8 +196,10 @@ class ElementComboIter
         size_t result = 0;
 
         for (auto const s : sb)
+        {
             if (has(s))
                 result++;
+        }
         return result;
     }
 
@@ -275,13 +279,17 @@ public:
             return currencyF();
         }();
         if (!has(SB::boundary))
+        {
             col.emplace_back(acc, cur, iss);
+        }
         else
+        {
             col.emplace_back(
                 STPathElement::Type::typeBoundary,
                 acc.value_or(AccountID{}),
                 cur.value_or(Currency{}),
                 iss.value_or(AccountID{}));
+        }
     }
 };
 
@@ -368,11 +376,17 @@ struct ExistingElementPool
         for (size_t id = 0; id < numCur; ++id)
         {
             if (id < 10)
+            {
                 snprintf(buf, bufSize, "CC%zu", id);
+            }
             else if (id < 100)
+            {
                 snprintf(buf, bufSize, "C%zu", id);
+            }
             else
+            {
                 snprintf(buf, bufSize, "%zu", id);
+            }
             currencies.emplace_back(to_currency(buf));
             currencyNames.emplace_back(buf);
         }
@@ -407,8 +421,10 @@ struct ExistingElementPool
         std::vector<IOU> ious;
         ious.reserve(numAct * numCur);
         for (auto const& a : accounts)
+        {
             for (auto const& cn : currencyNames)
                 ious.emplace_back(a[cn]);
+        }
 
         // create offers from every currency to every other currency
         for (auto takerPays = ious.begin(), ie = ious.end(); takerPays != ie; ++takerPays)