CLI2: copy mapfile for diff statistics

[JojoS62]

Summary of changes

copy the linker map file to target.elf.map.old. The memap.py statistics generator looks for a given filename +'.old'. If it exists, it generates the difference to previous module sizes as with CLI1.
Current behaviour is not copy the map file, so this feature is not yet available in CLI2 builds.

Impact of changes

The file(COPY_FILE, ...) function in cmake requires cmake 3.21, mbed is using currently 3.19. This PR maybe hold back until mbed upgrades to require cmake >= 3.21.

Migration actions required

Documentation

---

Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[x] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

---

Test results

[] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

---

Reviewers

---

[ciarmcom]

@JojoS62, thank you for your changes.
@ARMmbed/mbed-os-maintainers please review.

[ladislas]

Ah that's great! I really missed this feature and ended up implementing a workaround copying both old and new map files and then using diff. It works but not as nice.

[JojoS62]

yes, the only problem maybe that it requires a relative new cmake version. I have tried with other existing function, but without the RESULT 0 feature, the functions throw an error if the file not exists or wants to overwrite an existing one.

[0xc0170]

cmake_minimum_required(VERSION 3.19.0 FATAL_ERROR)

As it requires a new version, it should update the version in the main CMakeLists. As I know, we provided at least 2 fixes in CMake for armclang, it would be nice to have them. 3.21.3 should have them

[JojoS62]

a quick search shows that it will affect >100 CMakeLists.txt, a lot in the tests. I guess there is no common setting and all need to be updated?

I will try.

[mergify]

This PR cannot be merged due to conflicts. Please rebase to resolve them.

[JojoS62]

closing because of problems with rebase, I will create a new PR

[JojoS62]

replaced by #15117 due to rebase problems