v2.0.0 Add support for ESP32S2 and update ESP-IDF to 4.4 (#4996)

This is very much still work in progress and much more will change before the final 2.0.0

Some APIs have changed. New libraries have been added. LittleFS included.

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libraries/LITTLEFS/examples/LITTLEFS_PlatformIO/README.md

@@ -0,0 +1,68 @@
+# How to run on PlatformIO IDE
+
+- Download and extract to this project root a **mklittlefs** executable for your OS [from a zipped binary here](https://github.com/earlephilhower/mklittlefs/releases) 
+- Open **LITTLEFS_PlatformIO** folder
+- Run PlatformIO project task: **Upload Filesystem Image** 
+- Run PlatformIO project task: **Upload and Monitor**
+- You will see a Serial output like:
+```
+--- Miniterm on COM5  115200,8,N,1 ---
+--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
+ets Jun  8 2016 00:22:57
+
+rst:0x1 (POWERON_RESET),boot:0x13 (Snfigsip: 0, SPIWP:0xee
+clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
+mode:DIO, clock div:2
+load:0x3fff0018,len:4
+load:0x3fff001c,len:1044
+load:0x40078000,len:10044
+load:0x40080400,len:5872
+entry 0x400806ac
+Listing directory: /
+  FILE: /file1.txt  SIZE: 3  LAST WRITE: 2020-10-06 15:10:33
+  DIR : /testfolder  LAST WRITE: 2020-10-06 15:10:33
+Creating Dir: /mydir
+Dir created
+Writing file: /mydir/hello2.txt
+- file written
+Listing directory: /
+  FILE: /file1.txt  SIZE: 3  LAST WRITE: 2020-10-06 15:10:33
+  DIR : /mydir  LAST WRITE: 1970-01-01 00:00:00
+Listing directory: /mydir
+  FILE: /mydir/hello2.txt  SIZE: 6  LAST WRITE: 1970-01-01 00:00:00
+  DIR : /testfolder  LAST WRITE: 2020-10-06 15:10:33
+Listing directory: /testfolder
+  FILE: /testfolder/test2.txt  SIZE: 3  LAST WRITE: 2020-10-06 15:10:33
+Deleting file: /mydir/hello2.txt
+- file deleted
+Removing Dir: /mydir
+Dir removed
+Listing directory: /
+  FILE: /file1.txt  SIZE: 3  LAST WRITE: 2020-10-06 15:10:33
+  DIR : /testfolder  LAST WRITE: 2020-10-06 15:10:33
+Listing directory: /testfolder
+  FILE: /testfolder/test2.txt  SIZE: 3  LAST WRITE: 2020-10-06 15:10:33
+Writing file: /hello.txt
+- file written
+Appending to file: /hello.txt
+- message appended
+Reading file: /hello.txt
+- read from file:
+Hello World!
+Renaming file /hello.txt to /foo.txt
+- file renamed
+Reading file: /foo.txt
+- read from file:
+Hello World!
+Deleting file: /foo.txt
+- file deleted
+Testing file I/O with /test.txt
+- writing................................................................
+ - 1048576 bytes written in 12006 ms
+- reading................................................................
+- 1048576 bytes read in 547 ms
+Deleting file: /test.txt
+- file deleted
+Test complete
+```
+- If you have a module with more than 4MB flash, you can uncomment **partitions_custom.csv** in **platformio.ini** and modify the csv file accordingly