Add -in and -notin tests (#190)

Author: IISResetMe

examples/TheBigTestFile.ps1

@@ -390,6 +390,8 @@ if (10 -cgt 100) { }
 $a -is $b
 $b -contains $c
 $x -notcontains $c
+$c -in $b
+$c -notin $x
 $a -match $b
 $a -notmatch $b
 $x -like $c

spec/testfiles/syntax_test_TheBigTestFile.ps1

@@ -1006,6 +1006,10 @@ $b -contains $c
 #  ^ keyword.operator.comparison.powershell
 $x -notcontains $c
 #  ^ keyword.operator.comparison.powershell
+$c -in $b
+#  ^ keyword.operator.comparison.powershell
+$c -notin $x
+#  ^ keyword.operator.comparison.powershell
 $a -match $b
 #  ^ keyword.operator.comparison.powershell
 $a -notmatch $b