[Feedback] Conan Advanced - Tools as build_requires

The course suggests to avoid using in-recipe build_requires for common tools such as CMake and move them into profiles in order to leverage system-installed tools, while using exact versions of less common tools directly in the recipe.

While it's a bit off-topic to the course itself - It feels like it 'd produce an unsatisfactory user experience on both ends:
* For common tools, if the tool happen to not be present in the system, Conan will fail to build the package and will not help the user with a tip to include the tool into the profile.
* For less common tools, CCI encodes the exact version of a tool, meaning that users can exclude the tool from the recipe in a convenient way to use a tool in the system and they also have duplicated tools in the graph, because CCI forbids version ranges.

The reasoning in here feels a bit contradictionary to itself.

Start by reviewing the Conan Advanced course guidance on tools as build_requires, profiles, system-installed tools, and exact tool versions in recipes. Compare the two recommendations and document a consistent explanation that addresses missing common tools, optional system tools, and duplicated tools in the dependency graph.

Written by the indexing model from the issue text.