aws: set AWS_EB_PROFILE for the EB CLI (#7388)

Added AWS_EB_PROFILE environment variable to the AWS Plugin. The EB CLI uses this
variable instead of the primary AWS_PROFILE variable to keep track of what profile
it is using.

https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/eb-cli3-configuration.html

plugins/aws/aws.plugin.zsh

@@ -7,6 +7,7 @@ function agp {
 function asp {
   export AWS_DEFAULT_PROFILE=$1
   export AWS_PROFILE=$1
+  export AWS_EB_PROFILE=$1
 
   if [[ -z "$1" ]]; then
     echo AWS profile cleared.