rule: Fix pointless issue when using with (#907)

Fixes #904

I find the times to be comparable for the regal bundle +
a simple violating file.

```sh
regal $ go build && time ./regal lint .  --disable-all --enable=pointless-r
eassignment
Rule:           pointless-reassignment
Description:    Pointless reassignment of variable
Category:       style
Location:       thing.rego:10:6
Text:           foo := e with foo as 2
Documentation:  https://docs.styra.com/regal/rules/style/pointless-reassignment

201 files linted. 1 violation found in 1 file.

real    0m1.906s
user    0m6.344s
sys     0m0.244s
[3]regal $ bran
Current:  main
Switched to branch 'pointless'
Your branch is ahead of 'main' by 1 commit.
  (use "git push" to publish your local commits)
regal $ go build && time ./regal lint .  --disable-all --enable=pointless-reassignment
201 files linted. No violations found.

real    0m1.580s
user    0m2.930s
sys     0m0.109s
```

Signed-off-by: Charlie Egan <[email protected]>

bundle/regal/rules/style/pointless_reassignment.rego

@@ -21,19 +21,14 @@ report contains violation if {
 
 # pointless reassignment in rule body
 report contains violation if {
-	some call in ast.all_refs
+	some rule in input.rules
+	some expr in rule.body
 
-	call[0].value[0].type == "var"
-	call[0].value[0].value == "assign"
+	not expr["with"]
 
-	call[2].type == "var"
+	expr.terms[0].value[0].type == "var"
+	expr.terms[0].value[0].value == "assign"
+	expr.terms[2].type == "var"
 
-	violation := result.fail(rego.metadata.chain(), result.location(call))
-}
-
-assign_calls contains call if {
-	some call in ast.all_refs
-
-	call[0].value[0].type == "var"
-	call[0].value[0].value == "assign"
+	violation := result.fail(rego.metadata.chain(), result.location(expr.terms))
 }

bundle/regal/rules/style/pointless_reassignment_test.rego

@@ -50,3 +50,18 @@ test_pointless_reassignment_in_rule_body if {
 		"title": "pointless-reassignment",
 	}}
 }
+
+test_pointless_reassignment_in_rule_body_using_with if {
+	module := ast.with_rego_v1(`
+	foo := input
+
+	rule if {
+		bar := foo with input as "wow"
+
+		bar == true
+	}
+	`)
+
+	r := rule.report with input as module
+	r == set()
+}