Remove api from include path, add redirects

Can't have cores/rp2040/api in the include path because the Arduino API
dir has a "String.h" file.  On Windows, because it is case-insensitive
normally, this overrides the POSIX "string.h" header leading to bad
stuff.

Add manual redirect includes for commonly accessed headers in the
cores/rp2040 path instead.

cores/rp2040/Arduino.h

@@ -77,6 +77,11 @@ unsigned long millis();
 } // extern "C"
 #endif
 
+// Ancient AVR defines
+#define HAVE_HWSERIAL0
+#define HAVE_HWSERIAL1
+#define HAVE_HWSERIAL2
+
 #ifdef __cplusplus
 #include "SerialUSB.h"
 #include "SerialUART.h"

cores/rp2040/Client.h

@@ -0,0 +1 @@
+#include "api/Client.h"

cores/rp2040/IPAddress.h

@@ -0,0 +1 @@
+#include "api/IPAddress.h"

cores/rp2040/Interrupts.h

@@ -0,0 +1 @@
+#include "api/Interrupts.h"

cores/rp2040/Server.h

@@ -0,0 +1 @@
+#include "api/Server.h"

cores/rp2040/Stream.h

@@ -0,0 +1 @@
+#include "api/String.h"

cores/rp2040/Udp.h

@@ -0,0 +1 @@
+#include "api/Udp.h"

package/package_pico_index.template.json

@@ -74,49 +74,49 @@
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/aarch64-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "archiveFileName": "aarch64-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "checksum": "SHA-256:5064727a074c8bc8dff988e82bc2460c5f5610a04ec0a61ba233bdabe0499a24",
-                     "size": ""
+                     "size": "6075189"
                   },
                   {
                      "host": "arm-linux-gnueabihf",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/arm-linux-gnueabihf.openocd-d58c2ef5e.210328.tar.gz",
                      "archiveFileName": "arm-linux-gnueabihf.openocd-d58c2ef5e.210328.tar.gz",
                      "checksum": "SHA-256:12e61ebe727cb188fab25af174f0696ef86d629701f03f189965a725bd51275b",
-                     "size": ""
+                     "size": "6076094"
                   },
                   {
                      "host": "i686-pc-linux-gnu",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/i686-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "archiveFileName": "i686-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "checksum": "SHA-256:eaa89ac30556aaed5cd09fff4f46435f5a79c58d2060069db7606f9ecc9529ef",
-                     "size": ""
+                     "size": "6076262"
                   },
                   {
                      "host": "i686-mingw32",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/i686-w64-mingw32.openocd-d58c2ef5e.210328.zip",
                      "archiveFileName": "i686-w64-mingw32.openocd-d58c2ef5e.210328.zip",
                      "checksum": "SHA-256:65b8c96b94f1cc3ff13eb853138efb3a465150fb02d07c792f8b235d43b05061",
-                     "size": ""
+                     "size": "6378934"
                   },
                   {
                      "host": "x86_64-apple-darwin",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/x86_64-apple-darwin14.openocd-d58c2ef5e.210328.tar.gz",
                      "archiveFileName": "x86_64-apple-darwin14.openocd-d58c2ef5e.210328.tar.gz",
                      "checksum": "SHA-256:b8a759d7ac20643641285b0b05473b853e50739dd254b2294f5d1802ff0e15ca",
-                     "size": ""
+                     "size": "6076324"
                   },
                   {
                      "host": "x86_64-pc-linux-gnu",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/x86_64-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "archiveFileName": "x86_64-linux-gnu.openocd-d58c2ef5e.210328.tar.gz",
                      "checksum": "SHA-256:9ff31fc92d6f86503d1750d009fec7e7c8c185c7956b140c4b78ee029d31c19c",
-                     "size": ""
+                     "size": "6076342"
                   },
                   {
                      "host": "x86_64-mingw32",
                      "url": "https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.1.0-a/x86_64-w64-mingw32.openocd-d58c2ef5e.210328.zip",
                      "archiveFileName": "x86_64-w64-mingw32.openocd-d58c2ef5e.210328.zip",
                      "checksum": "SHA-256:8f1ddd64b0a6f83f94437d509bb28cdd45ad481bb161c170d57a6736f75087ec",
-                     "size": ""
+                     "size": "6378956"
                   }
                ]
             },