Add deprecation message for Process
minor #12696 [2.7][Process] Add deprecation message for component (romainneutron)

This PR was merged into the 2.7 branch.

Discussion
----------

[2.7][Process] Add deprecation message for component

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT

Commits
-------

b9a6b71 Add deprecation message for Process