[substitutions] implement !literal (#10785)

tests/unit_tests/fixtures/substitutions/00-simple_var.approved.yaml

@@ -1,7 +1,11 @@
 substitutions:
+  substituted: 99
   var1: '1'
   var2: '2'
   var21: '79'
+  value: 33
+  values: 44
+
 esphome:
   name: test
 test_list:
@@ -19,3 +23,6 @@ test_list:
   - ${ undefined_var }
   - key1: 1
     key2: 2
+  - Literal $values ${are not substituted}
+  - ["list $value", "${is not}", "${substituted}"]
+  - {"$dictionary": "$value", "${is not}": "${substituted}"}

tests/unit_tests/fixtures/substitutions/00-simple_var.input.yaml

@@ -2,9 +2,12 @@ esphome:
   name: test
 
 substitutions:
+  substituted: 99
   var1: "1"
   var2: "2"
   var21: "79"
+  value: 33
+  values: 44
 
 test_list:
   - "$var1"
@@ -21,3 +24,6 @@ test_list:
   - ${ undefined_var }
   - key${var1}: 1
     key${var2}: 2
+  - !literal Literal $values ${are not substituted}
+  - !literal ["list $value", "${is not}", "${substituted}"]
+  - !literal {"$dictionary": "$value", "${is not}": "${substituted}"}