Convert diagrams from Mscgen and Graphviz to Mermaid

Caveats:

mermaid_cli is required, but it fails on Windows (WSL2). It requires Google Chrome, but it needs to be installed seperately and mermaid_cli needs to be launched with a puppeteer config file where executablePath is set to /usr/bin/google-chrome. Example:
```
mermaid_params = ['-p', 'source/puppeteerConfigFile.json']
```
and source/puppeteerConfigFile.json:
```
{
"executablePath": "/usr/bin/google-chrome"
}
```
We also need sphinxcontrib-mermaid. But in order for the diagrams to look good, we need to tweak the configuration settings using mermaid_sequence_config, but this setting seems to be ignored when using html output unless mermaid_output_format is set to something other than raw (default), e.g. png. However, this makes capabilities such as zoom no longer work with the html output.
There seems to be a bug in sphinxcontrib-mermaid (at least in the one shipped with Ubuntu 23.10) where the mermaid_sequence_config does not work correctly. But mermaid_params can be used instead
State diagrams doesn't support dotted lines

EDIT: We skip the WSL2 workaround

rsmp-nordic / rsmp_core