Allow non-go project to install and user sicher

[eltNEG]

Description

In the current implementation of sicher, users needs to have golang installed. Also, users need to import sicher into a go project for it to work.

I will like it if sicher can be installed as a cli binary that updates the envirenment variables of the terminal where sicher setenv is ran.

Proposed solution

• build sicher binary for different os so that users can download and install sicher binary
• implement a new flag that allows sicher to decrypt and update the env variables of the current terminal.

Alternative

The proposed solution can be ignored if sicher wants to continue as a go module instead of a cli tool.