Revert/remove unmaintained ports 2026 (#1324)

* Removed unmaintained ports/uip folder

* Removed unmaintained ports/arduino_uno folder

* Removed unmaintained ports/pic18* folders and references.

* Removed unmaintained ports/rx62n folder.

license/ISC

@@ -1,26 +0,0 @@
-Valid-License-Identifier: ISC
-SPDX-URL: https://spdx.org/licenses/ISC.html
-Usage-Guide:
-  Do not use. Currently only one arduino file is using this license.
-
-  To use the ISC License put the following SPDX tag/value pair into a
-  comment according to the placement guidelines in the licensing rules
-  documentation:
-    SPDX-License-Identifier: ISC
-License-Text:
-
-ISC License
-
-Copyright (c) <year> <copyright holders>
-
-Permission to use, copy, modify, and/or distribute this software for any
-purpose with or without fee is hereby granted, provided that the above
-copyright notice and this permission notice appear in all copies.
-
-THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
-OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
-CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.