AK: Remove StringBuilder::build() in favor of to_deprecated_string()

Having an alias function that only wraps another one is silly, and
keeping the more obvious name should flush out more uses of deprecated
strings.
No behavior change.

Userland/Applications/Spreadsheet/Cell.cpp

@@ -42,7 +42,7 @@ void Cell::set_data(JS::Value new_data)
     StringBuilder builder;
 
     builder.append(new_data.to_string_without_side_effects());
-    m_data = builder.build();
+    m_data = builder.to_deprecated_string();
 
     m_evaluated_data = move(new_data);
 }

Userland/Applications/Spreadsheet/CellType/Format.cpp

@@ -43,7 +43,7 @@ DeprecatedString format_double(char const* format, double value)
     auto putch = [&](auto, auto ch) { builder.append(ch); };
     printf_internal<decltype(putch), PrintfImpl, double, SingleEntryListNext>(putch, nullptr, format, value);
 
-    return builder.build();
+    return builder.to_deprecated_string();
 }
 
 }

Userland/Applications/Spreadsheet/Spreadsheet.cpp

@@ -745,7 +745,7 @@ DeprecatedString Sheet::generate_inline_documentation_for(StringView function, s
     }
 
     builder.append(')');
-    return builder.build();
+    return builder.to_deprecated_string();
 }
 
 DeprecatedString Position::to_cell_identifier(Sheet const& sheet) const