Summary

Users have requested a way to make the WROVER module to boot faster.
It takes about 1 second to boot in a 4MB PSRAM configuration because of SPI RAM Test routine.

This PR adds a function to ESP32 Arduino that allows the user to programmatically tell Arduino not to spend time on PSRAM test. The default behavior is to test it.

The API is BYPASS_SPIRAM_TEST(bool)

Example:

BYPASS_SPIRAM_TEST(true);  // not declaring it or using BYPASS_SPIRAM_TEST(false) will run SPI RAM Test

void setup() {
  Serial.begin(115200);
  Serial.println("\n --- SPIRAM test bypass!");
  Serial.println("Check how long does it take to boot in a WROVER module.");
}

void loop() {
  static uint8_t count = 0;
  Serial.print("-");
  delay(500);
  if (++count == 32) {
    count = 0;
    Serial.println();
  }
}

Impact

The user decides if SPI RAM shall be tested before starting or not. This is not forced anymore by software.
Documentation is necessary (@pedrominatel)

Related links

Fixes #5737