feat(map): config.get lookups from configurable roots

We avoid compatibility break with user pillars by looking up
configuration values using `config.get` in configurable roots.

We provide a new parameter `map_jinja:config_get_roots` in the formula
`parameters/defaults.yaml`to retrives values not only from
`tplroot=openssh` but from `sshd_config` and `ssh_config` too.

We need to update the `_mapdata` reference files to include the new
`map_jinja:config_get_roots`.

test/integration/default/files/_mapdata/amazonlinux-2.yaml

@@ -1,6 +1,11 @@
 # yamllint disable rule:indentation rule:line-length
 # Amazon Linux-2
 ---
+map_jinja:
+  config_get_roots:
+  - openssh
+  - sshd_config
+  - ssh_config
 openssh:
   absent_dsa_keys: false
   absent_ecdsa_keys: false