Previous "dry-run"-esque behavior was leaky, resulting in a not-so-dry run.

- Subcommand spec tests for exec should not actually call cli.execute!, so intercept them.
- Process all early-exit flags first

(BKR-1168) Exit early on --version, --help, and --parse-only

If a frozen string was passed into the logging routines, it would
fail with an exception about strings being frozen.  This change
allows frozen strings to be logged.  For example:

irb(main):001:0> foo = "hello there"
=> "hello there"
irb(main):002:0> foo.freeze
=> "hello there"
irb(main):003:0> foo.to_s.force_encoding('UTF-8')
RuntimeError: can't modify frozen String
	from (irb):3:in `force_encoding'
	from (irb):3
	from /Users/jnewman/.rbenv/versions/2.3.1/bin/irb:11:in `<main>'
irb(main):004:0> foo.to_s.dup.force_encoding('UTF-8')
=> "hello there"

…rozen-strings

(maint) allow logging of frozen strings

Also includes a rebase workflow.

…1526)

* (BKR-1481) Introduce Beaker::Shared::FogFileParser.parse_fog_file()

Introduces a shared module for parsing .fog credential files, with descriptive error messages and spec coverage.

* (BKR-1481) Fix environment vairable handling

Also updates examples in documentation.

* (BKR-1481) Rename FogFileParser to FogCredentials

* (BKR-1481) Refactor .fog credentials exception handling

* (BKR-1481) Don't forget the changelog

(BKR-816) Expand contribution guidelines with PR requirements

…xec (#1528)

* (BKR-1393) Update exec help description

Clarify behavior to support passing multiple test files, directories, or suites as a comma-separated list, as long as that list is homogeneous.

* (BKR-1393) Update docs/tutorials/subcommands.md

Clarify that exec accepts comma-separated list of tests.

[skip ci]

(MAINT) release 3.37.0