feat: allow environment variables to be set

[anoriqq]

$QPM_ENV is environment file.

echo "{environment_variable_name}={value}" >> $QPM_ENV

example usage

aquifer file

install:
  linux:
    run:
      - echo NAME=world >> $QPM_ENV
      - echo "hello ${NAME}"

output

[1/2] echo NAME=world >> $QPM_ENV
[2/2] echo "hello ${NAME}"
hello world
[complete]