Revisit espup update and espup uninstall

[SergioGasquez]

Thanks @jessebraham for opening this discussion and feedback on this topic.

Motivations

At the moment, both commands depend on the config file. The config file is populated when espup install is executed but it might be deleted or a user might already come to espup with an environment installed with rust-build scripts.

If the config file is not present, instead of failing we could do some assumptions and run them successfully.

Solution

• For espup update (WIP: https://github.com/esp-rs/espup/tree/fix/no-config-file): Since there is no way to know which version of the toolchain we have installed. (cargo +esp --version is not an option since we use an extended version of semver and, sometimes, the last digit is quite relevant). What we could do is uninstall the current version and install the required version (latest if no argument is provided).
  • It could happen that you already have the latest toolchain installed, and it would be installing the same version.
  • When updating we will populate a config file with all the information that we have, so it can be used for futures updates
• For espup uninstall: I'm still not sure how to handle it, we could probably just delete the $RUSTUP_HOME/toolchain/esp folder.
  • Deleting anything under $HOME/.espressif could be risky as we don't know if it was installed for Rust environment of for ESP-IDF.