Add output for "secrets" and "configs" on stack deploy

[thaJeztah]

When deploying a stack from a compose file, the output did not show
that a secret or config was created. This patch adds messages for these.

Create a configuration file and compose file:

$ cat > config.yml <<EOF
hello: world
EOF

$ cat > secret.txt <<EOF
p@ssw0rd
EOF


$ cat > docker-compose.yml <<EOF
version: "3.3"
services:
   test:
     image: nginx:alpine
     configs:
     - source: myconfig
       target: /my-config.yml
     secrets:
     - source: mysecret
       target: /my-secret.txt
configs:
  myconfig:
    file: ./config.yml
secrets:
  mysecret:
    file: ./secret.txt
EOF

Before this patch is applied:

$ docker stack deploy -c docker-compose.yml example

Creating network example_default
Creating service example_test

After this patch is applied:

$ docker stack deploy -c docker-compose.yml example
Creating network example_default
Creating secret example_mysecret
Creating config example_myconfig
Creating service example_test

- What I did

Added additional messages during docker stack deploy

- How to verify it

See steps above

- Description for the changelog

* Add informational messages about creating `secrets` and `configs` during `docker stack deploy` [docker/cli#593](https://github.com/docker/cli/pull/593)

- A picture of a cute animal (not mandatory but encouraged)

[codecov-io]

Codecov Report

Merging #593 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #593      +/-   ##
==========================================
- Coverage   49.41%   49.41%   -0.01%     
==========================================
  Files         208      208              
  Lines       17184    17186       +2     
==========================================
  Hits         8492     8492              
- Misses       8260     8262       +2     
  Partials      432      432

[vdemeester]

s/secret/config/ 👼

[thaJeztah]

thx 😅 fixed

[dnephin]

LGTM

[cpuguy83]

LGTM