Refactorization of ot repos (#7139)

* [K32W] Use the new ot-nxp repo

OpenThread maintainers decided to split the big OT repo (core OT stack + vendor example)
in several repos: one repo containing the OT stack, then each vendor has a separate repo
with its example (the vendor repo contains the OT stack repo as a submodule).

This commit allows using the ot-nxp repo inside PCHIP. Only the platform files from ot-nxp
are used, the OT stack repo used is still the one from third_party/openthread/repo.

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Use the new ot-{efr32/qorvo} repos

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Restyled by whitespace

* Restyled by clang-format

* Restyled by gn

* Restyled by shfmt

* Fix ot submodules

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Remove TODOs

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Restyled by clang-format

* Remove ot-efr from .gitsubmodules

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Fix ot-efr submodule

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* * Update QPG6100 OpenThreadConfig.h (UART->HDLC)

* [K32W] Add a GN build arg for enabling/disabling the OT CLI

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* Restyled by clang-format

* Restyled by gn

* Fix define naming

Signed-off-by: Doru Gucea <doru-cristian.gucea@nxp.com>

* * Removing ot_<platform>.gni files - moved ot root var to platforms
* Re-enabled CLI on QPG6100 - introducing CLI flag in DeviceConfig.h

* Fix to efr buld to support openthread repo update

Co-authored-by: Restyled.io <commits@restyled.io>
Co-authored-by: Timothy Maes <timothy.maes@qorvo.com>
Co-authored-by: jmartinez-silabs <junior.martinez@silabs.com>
diff --git a/examples/build_overrides/ot_qorvo.gni b/examples/build_overrides/ot_qorvo.gni
new file mode 100644
index 0000000..109644c
--- /dev/null
+++ b/examples/build_overrides/ot_qorvo.gni
@@ -0,0 +1,18 @@
+# Copyright (c) 2021 Project CHIP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+declare_args() {
+  openthread_qorvo_root =
+      "//third_party/connectedhomeip/third_party/openthread/ot-qorvo"
+}