Add packages_to_install method

[ekohl]

This splits the existing validate_host into a method to just determine the packages to install and one that actually installs them. This makes it possible for beaker-docker to reuse the logic.

[codecov]

Codecov Report

Merging #1718 (de47a1a) into master (3c32c5b) will decrease coverage by 21.17%.
The diff coverage is 57.14%.

❗ Current head de47a1a differs from pull request most recent head 06bcf25. Consider uploading reports for the commit 06bcf25 to get more accurate results

@@             Coverage Diff             @@
##           master    #1718       +/-   ##
===========================================
- Coverage   74.64%   53.47%   -21.18%     
===========================================
  Files          82       82               
  Lines        4863     4868        +5     
===========================================
- Hits         3630     2603     -1027     
- Misses       1233     2265     +1032     

Impacted Files	Coverage Δ
lib/beaker/host_prebuilt_steps.rb	55.81% <57.14%> (-17.50%)	⬇️
lib/beaker/test_suite.rb	14.08% <0.00%> (-74.65%)	⬇️
lib/beaker/shared/repetition.rb	27.27% <0.00%> (-72.73%)	⬇️
lib/beaker/shared/fog_credentials.rb	24.00% <0.00%> (-72.00%)	⬇️
lib/beaker/local_connection.rb	22.64% <0.00%> (-71.70%)	⬇️
lib/beaker/options/hosts_file_parser.rb	38.88% <0.00%> (-61.12%)	⬇️
lib/beaker/test_case.rb	34.56% <0.00%> (-56.80%)	⬇️
lib/beaker/hypervisor.rb	28.12% <0.00%> (-56.25%)	⬇️
lib/beaker/host.rb	28.23% <0.00%> (-52.05%)	⬇️
lib/beaker/shared/semvar.rb	45.65% <0.00%> (-47.83%)	⬇️
... and 29 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3c32c5b...06bcf25. Read the comment docs.

[ekohl]

I forgot this was already a PR and merged another one.