[rspec] Adopt Hiera v3 lookups with RSpec tests

To satisfy Hiera lookups (as opposed to purely 'fact' based references)
RSpec tests now have their own respective Hiera hierarchy defined at:
'site/profiles/fixtures/hiera.yaml'. All existing (and future) RSpec tests
will now perform "Automatic Parameter Lookups" only falling back to
in-class default values should the corresponding key not be found.

The 'datadir' path to the RSpec test directory is relative to the
'Profiles' module's 'root' directory: 'site/profiles'. As of this commit
the "data-in-module" pattern is not currently utilised and consequently
dedicated RSpec specific Hiera data files are consumed.

The 'ghoneycutt-ssh' community module utilises a deprecated Hiera
function, 'hiera_hash', for performing a "deep" merge of an explicit
key: 'ssh::keys'. This is addressed in the same manner as:
c3a17e3e896ad24599d6f9274cc8f37a45844e41.

Unfortunately Hiera v3 had to be adopted as the Ruby gem 'rspec-puppet'
utilised by `pdk` is unable to parse Hiera v5 configuration file syntax.

Related links regarding Hiera v3 & puppet-rspec limitations:

* rodjek/rspec-puppet#762

* rodjek/rspec-puppet#551

* https://tickets.puppetlabs.com/browse/HI-598

site/profiles/spec/fixtures/data/common.yaml

@@ -0,0 +1,7 @@
+---
+profiles::ssh::keys:
+  'raft.com':
+    user: 'debian'
+    type: 'ssh-rsa'
+    key:  'AAAAB3NzaC1yc2EAAAADAQABAAABAQCvgu7p7cM17pL41bfJu+9VbH5t+APGnqxHQRdG2qlAr2TTKzlCxVslau7a5tay2lGJ757dNE6mrGVGwVDMorTADU9eqlA2ajwVTQpDtmblUSVzXDutKop/KPyDCnh8I+1mIgGp4jm1Fa0AP0LqJziY8WtS9waNphwMFjw+xCAGxI+a8dt49QrtmGonMouxMyRRB5pjzKjAPfVazsK4mCtWGvHX5m0Q+PCjd0DZPRflD1OuBvTG7KFoDVGxwDJqOIjAZ4vBkF/wO7wpsoKS9K2uNEhPEysR4JFbZbCyVgVXp6vint11025YOTjSHldQSZcEwbfgZOAfl09Qb8Um03ET'
+ssh::keys: "%{alias('profiles::ssh::keys')}"

site/profiles/spec/fixtures/hiera.yaml

@@ -0,0 +1,7 @@
+---
+:backends:
+  - yaml
+:yaml:
+  :datadir: './spec/fixtures/data'
+:hierarchy:
+  - 'common'

site/profiles/spec/spec_helper.rb

@@ -41,6 +41,7 @@
     Puppet.settings[:strict_variables] = true
   end
   c.filter_run_excluding(bolt: true) unless ENV['GEM_BOLT']
+  c.hiera_config = File.expand_path(File.join(__FILE__, '../fixtures/hiera.yaml'))
   c.after(:suite) do
   end
 end