Cleanups to "dx find projects"

* Remove blank line at end of (non-brief) output
* Don't buffer entire result set in memory
* Don't update cached_project_names since it never gets read
* Conform to PEP 8 whitespace and line length guidelines
* Chip away at the monolithic test test_dx_actions in favor of more
  specific test suites
PTFM-7932 Lower findProjects query page size for "dx select"

The previous page size was 100. Since the user is unlikely to page
through to 100 results in 10s, we only fetch 10 results initially.
PTFM-12607 Improving bash helper variables

Summary:
1. Refactoring of code, so as to acheive sharing, between local and remote execution.
2. Adding several bash variables available to the application: filenames, prefixes, and paths.

Test Plan: additional app for testing.

Reviewers: klai

Reviewed By: klai

Subscribers: psung

Differential Revision: https://phabricator.dnanexus.com/D88
PTFM-13569 dx cp: print exists array properly
Revert "PTFM-12607 Improving bash helper variables"

This reverts commit f42f3f8d4d7fbd6936835ad3a428082a85711a81.
Changelog and version updates for v0.122.0