Add ability to disable .env.local file writes

[gergesh]

I already manage my configuration on my own, using direnv and various configuration files.
It would be great being able to stop the convex cli from writing to .env.local when I switch deployment environments

[gergesh]

Seems like it's just a matter of having the envs actually configured, I initially thought the correct deployment (prod vs dev) had to be set and constantly changes the .env.local file. Closing

[gergesh]

Reopening because apparently it is like I initially thought
Even if when I have CONVEX_DEPLOYMENT and EXPO_PUBLIC_CONVEX_URL set, .env.local is still appended