feat(summary): add vars, env, and requires display (#2524)

testdata/summary-vars-requires/testdata/TestSummaryWithVarsAndRequires-shell-vars.golden

@@ -0,0 +1,10 @@
+task: with-sh-var
+
+Task with shell variable
+
+vars:
+  DYNAMIC_VAR: sh: echo "world"
+  STATIC_VAR: "hello"
+
+commands:
+ - echo 

testdata/summary-vars-requires/testdata/TestSummaryWithVarsAndRequires-vars-and-requires.golden

@@ -0,0 +1,13 @@
+task: mytask
+
+It does things and has optional and required variables.
+
+vars:
+  OPTIONAL_VAR: "hello"
+
+requires:
+  vars:
+    - REQUIRED_VAR
+
+commands:
+ - echo hello