[Process] Fix ExecutableFinder with open basedir
bug #11179 [Process] Fix ExecutableFinder with open basedir (cs278)

This PR was squashed before being merged into the 2.3 branch (closes #11179).

Discussion
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[Process] Fix ExecutableFinder with open basedir

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

This fixes the `ExecutableFinder` object to properly fetch the `open_basedir` setting, also added a bunch of tests for the `find()` method.

Commits
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b8f8c0e [Process] Fix ExecutableFinder with open basedir