Split TestSuite methods between test run methods
and packet related methods.

Depends-on: series-36111 ("Split DTS framework and public API")

Signed-off-by: Paul Szczepanek <paul.szczepanek@arm.com>
Reviewed-by: Luca Vizzarro <luca.vizzarro@arm.com>
---
 doc/api/dts/api.packet.rst  |   8 +
 doc/api/dts/api.rst         |   4 +-
 doc/api/dts/api.test.rst    |   8 +
 doc/guides/tools/dts.rst    |   2 +-
 dts/api/packet.py           | 311 ++++++++++++++++++++++++++++++++++++
 dts/api/test.py             | 126 +++++++++++++++
 dts/framework/test_suite.py | 305 +----------------------------------
 7 files changed, 460 insertions(+), 304 deletions(-)
 create mode 100644 doc/api/dts/api.packet.rst
 create mode 100644 doc/api/dts/api.test.rst
 create mode 100644 dts/api/packet.py
 create mode 100644 dts/api/test.py

diff --git a/dts/api/packet.py b/dts/api/packet.py
new file mode 100644
index 0000000000..bf6f3e1be8
--- /dev/null
+++ b/dts/api/packet.py
@@ -0,0 +1,311 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2025 Arm Limited
+
+"""Features common to all test suites.
+
+The module defines the :class:`TestSuite` class which doesn't contain any test cases, and as such
+must be extended by subclasses which add test cases. The :class:`TestSuite` contains the basics
+needed by subclasses:
+
+    * Testbed (SUT, TG) configuration,
+    * Packet sending and verification,
+    * Test case verification.
+"""

+