Look into cost of executing all commands in shell process

[brettcannon]

When we run commands in a system call we don't seem to inherit the current environment and we don't seem to execute in a shell. It might be good to see if (a) we can inherit the current environment, (b) execute in a shell, and (c) if there's any maintenance/perf cost to doing this. I suspect this will have less of a surprise for users if we can do this.

[brettcannon]

#2422 determined that we are not executing in a shell.

[brettcannon]

Thanks to conda run this is less of a concern. Plus with the shift to tools extensions and language servers this is less of a concern here. Closing as out of date.