twister: Add quarantine feature

Adds feature allowing to use yaml file with dictionaries defining
tests to be quarantined (extra arg "--quarantine-list FILENAME").
The dictionaries are validated according to the proper schema
and loaded.

A flat list is created containing quarantined configurations
(configuration = platform + scenario). Configurations under quarantine
are skipped and get "Quarantine" as a reason in the results reports.

A "comment" can be added to a quarantine entry in the quarantine yaml
with more details (e.g. issue #) and it will be also added to
the report.

The status of tests under quarantine can be verify if
`--quarantine-verify` is used in addition to
"--quarantine-list FILENAME". Using these args will make twister skip
all tests which are not on the quarantine list.

Signed-off-by: Maciej Perkowski <Maciej.Perkowski@nordicsemi.no>

scripts/schemas/twister/quarantine-schema.yaml

@@ -0,0 +1,31 @@
+#
+# Schema to validate a YAML file providing the list of configurations
+# under quarantine
+#
+# We load this with pykwalify
+# (http://pykwalify.readthedocs.io/en/unstable/validation-rules.html),
+# a YAML structure validator, to validate the YAML files that provide
+# a list of configurations (scenarios + platforms) under quarantine
+#
+type: seq
+matching: all
+sequence:
+  - type: map
+    required: yes
+    matching: all
+    mapping:
+      "scenarios":
+        type: seq
+        required: true
+        sequence:
+          - type: str
+          - unique: True
+      "platforms":
+        required: true
+        type: seq
+        sequence:
+          - type: str
+          - unique: True
+      "comment":
+        type: str
+        required: false