age: Fix feature flag combination bugs in cli_common module

[str4d]

Closes #515.

[codecov]

Codecov Report

Attention: Patch coverage is 71.05263% with 11 lines in your changes missing coverage. Please review.

Project coverage is 50.74%. Comparing base (0cf17d9) to head (7e3c62b).

Files	Patch %	Lines
age/src/cli_common/recipients.rs	70.58%	10 Missing ⚠️
age/src/cli_common/identities.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #516      +/-   ##
==========================================
- Coverage   50.83%   50.74%   -0.09%     
==========================================
  Files          42       42              
  Lines        4058     4075      +17     
==========================================
+ Hits         2063     2068       +5     
- Misses       1995     2007      +12     

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