Postpone breaking changes for another PR

I think we need to put a little more thought into whether we really
want the build time in each of these, or whether it should be just
the config_hash (perhaps extended with version, and in some cases
the component's own serial number or other identifier).

So put the old compilation_time_ and its access methods back, so
this PR only adds the *new* fields. We can migrate users over and
then remove the compilation_time_ separately.

tests/dummy_main.cpp

@@ -12,7 +12,7 @@
 using namespace esphome;
 
 void setup() {
-  App.pre_setup("livingroom", "LivingRoom", "comment", false);
+  App.pre_setup("livingroom", "LivingRoom", "comment", __DATE__ ", " __TIME__, false);
   auto *log = new logger::Logger(115200, 512);  // NOLINT
   log->pre_setup();
   log->set_uart_selection(logger::UART_SELECTION_UART0);