tools: Increase the minimal supported CMake version to 3.16

This updates the minimal supported version of CMake to 3.16, which in turn enables us to use more CMake features and have a cleaner build system.
This is the version that provides most new features and also the one we use in our latest docker image for CI.

components/mqtt/host_test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 set(COMPONENTS main)

examples/protocols/mqtt/ssl/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/ssl_ds/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/ssl_mutual_auth/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/ssl_psk/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/tcp/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/ws/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

examples/protocols/mqtt/wss/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

tools/test_apps/protocols/mqtt/build_test/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.

tools/test_apps/protocols/mqtt/publish_connect_test/CMakeLists.txt

@@ -1,6 +1,6 @@
 # The following four lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.16)
 
 # (Not part of the boilerplate)
 # This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.