More IAR support

[HiFiPhile]

Describe the PR

Add IAR project connection files, which can be used to automatically import tusb stack & examples into IAR project.

Since SDKs in hw\mcu only have GCC's cstartup file (and there are too many MCUs for me...), a buildable IAR project need to be created before import tusb.

Example's source files (main.c, tusb_config.h, etc.) will be copied to project's directory, os they can be edited safely.

tools/iar.ipcf only contains the stack, *.ipcf inside examples contain stack & example.

iar_gen.py is used to generate *.ipcf inside examples from tools/iar.ipcf.

Additional context
I'm going to add a few words in docs/reference/getting_started.rst, for image I create a folder assert in docs/reference ?

[hathach]

This is great and I am sure IAR user will find it helpful. However, as you mentioned ipcf only add source files as they appear in the actual file system and not buildable. Therefore it is not too useful IMHO.

To be honest, I have a mixed feeling about adding these file. I don't use IAR at all therefore cannot and won't be able to maintain these project file in the future. My experience with IDE is that they are super nice with specific project on specific MCUs with all of its great debug tool. However, adding cross-platform factor such as mcus, it becomes too time consuming to maintain (too many clicks to config/change).

Anyway, It is still useful to have tools/iar_gen.py and iar.icpf (maybe rename the later to iar_template.icpf). For the example ipcf, maybe just let user to generate those on their own. That way we don't have to maintain those files.

[HiFiPhile]

For the example ipcf, maybe just let user to generate those on their own. That way we don't have to maintain those files.

Yes it's easier to maintain less files... I've removed examples and added doc.

[hathach]

superb ! thank you very much for your PR. It look perfect now