[uart] Multiple ESP32 features and fixes (#8103)

Co-authored-by: Keith Burzinski <kbx81x@gmail.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick@koston.org>

esphome/components/uart/uart_component.cpp

@@ -20,5 +20,13 @@ bool UARTComponent::check_read_timeout_(size_t len) {
   return true;
 }
 
+void UARTComponent::set_rx_full_threshold_ms(uint8_t time) {
+  uint8_t bytelength = this->data_bits_ + this->stop_bits_ + 1;
+  if (this->parity_ != UARTParityOptions::UART_CONFIG_PARITY_NONE)
+    bytelength += 1;
+  int32_t val = clamp<int32_t>((this->baud_rate_ / (bytelength * 1000 / time)) - 1, 1, 120);
+  this->set_rx_full_threshold(val);
+}
+
 }  // namespace uart
 }  // namespace esphome