Attempt to read espflash config from project_dir/.config/espflash.toml

[svenstaro]

The config is currently only read system-wide ($HOME/.config/espflash/espflash.toml) but this is annoying if you work on multiple unrelated projects. I think cargo-espflash should first attempt to read project_dir/.config/espflash.toml and fall back to the system config if the former config doesn't exist.

[galah92]

Would also like a way to have a local config file (that take precedence over the global one). That would help multiple developers working on the same project were each has it's own serial mapping.
If there's another way to achieve that, I'll be happy to hear about it.
Also, our team mostly use the Cargo Runner (.cargo/config.toml), to run espflash, so ideally it would be a solution that supports this.

[SergioGasquez]

Soon, we will start working towards espflash 3.0 where we will evaluate the different configuration options, at the moment we have several ways (files, env variables…) and this might change in the future, thanks for the suggestion