1. Support built-in ADC for I2S.
2. Modify code of ADC, made no change to the original APIs.
3. Add APIs in I2S:
esp_err_t i2s_set_adc_mode(adc_unit_t adc_unit, adc1_channel_t adc_channel);
4. Add I2S ADC/DAC example code.
5. add old-fashion definition to make it more compatible
6. replase spi_flash_ APIs with esp_partition_ APIs
7. add example of generating audio table from wav
8. change example sound
