Remove id from paths to instances in style warnings

Fixes kaitai-io/kaitai_struct#920

Error count: 62 -> 58 (-4). Fixed:

[info] - style_bad_len_inst_pos *** FAILED ***
[info]   [style_bad_len_inst_pos.ksy: /instances/size_of_foo/id:
[info]          warning: use `len_foo` instead of `size_of_foo`, given that it's only used as a byte size of `foo` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ]
[info]     did not equal
[info]   [style_bad_len_inst_pos.ksy: /instances/size_of_foo:
[info]          warning: use `len_foo` instead of `size_of_foo`, given that it's only used as a byte size of `foo` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ] (SimpleMatchers.scala:34)
[info] - style_bad_len_inst_value *** FAILED ***
[info]   [style_bad_len_inst_value.ksy: /instances/size_of_foo/id:
[info]          warning: use `len_foo` instead of `size_of_foo`, given that it's only used as a byte size of `foo` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ]
[info]     did not equal
[info]   [style_bad_len_inst_value.ksy: /instances/size_of_foo:
[info]          warning: use `len_foo` instead of `size_of_foo`, given that it's only used as a byte size of `foo` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ] (SimpleMatchers.scala:34)
[info] - style_bad_num_inst_pos *** FAILED ***
[info]   [style_bad_num_inst_pos.ksy: /instances/size_of_foo/id:
[info]          warning: use `num_foos` instead of `size_of_foo`, given that it's only used as repeat count of `foos` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ]
[info]     did not equal
[info]   [style_bad_num_inst_pos.ksy: /instances/size_of_foo:
[info]          warning: use `num_foos` instead of `size_of_foo`, given that it's only used as repeat count of `foos` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ] (SimpleMatchers.scala:34)
[info] - style_bad_num_inst_value *** FAILED ***
[info]   [style_bad_num_inst_value.ksy: /instances/size_of_foo/id:
[info]          warning: use `num_foos` instead of `size_of_foo`, given that it's only used as repeat count of `foos` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ]
[info]     did not equal
[info]   [style_bad_num_inst_value.ksy: /instances/size_of_foo:
[info]          warning: use `num_foos` instead of `size_of_foo`, given that it's only used as repeat count of `foos` (see https://doc.kaitai.io/ksy_style_guide.html#attr-id)
[info]   ] (SimpleMatchers.scala:34)

shared/src/main/scala/io/kaitai/struct/precompile/StyleCheckIds.scala

@@ -39,33 +39,53 @@ class StyleCheckIds(specs: ClassSpecs) extends PrecompileStep {
       }
   }
 
+  /**
+    * @param spec Owner of `attr`
+    * @param attr Attribute that references attribute with probably not-conformant name
+    */
   def getSizeRefProblem(spec: ClassSpec, attr: MemberSpec): Option[CompilationProblem] = {
     getSizeReference(spec, attr.dataType).flatMap(sizeRefAttr => {
       val existingName = sizeRefAttr.id.humanReadable
       val goodName = s"len_${attr.id.humanReadable}"
       if (existingName != goodName) {
+        // Report error at position where referenced attribute is defined.
+        // Add `id` for attributes in `seq`, do not add for instances
+        val path = sizeRefAttr match {
+          case _: InstanceSpec => sizeRefAttr.path
+          case _ => sizeRefAttr.path :+ "id"
+        }
         Some(StyleWarningSizeLen(
           goodName,
           existingName,
           attr.id.humanReadable,
-          ProblemCoords(path = Some(sizeRefAttr.path ++ List("id")))
+          ProblemCoords(path = Some(path))
         ))
       } else {
         None
       }
     })
   }
 
+  /**
+    * @param spec Owner of `attr`
+    * @param attr Attribute that references attribute with probably not-conformant name
+    */
   def getRepeatExprRefProblem(spec: ClassSpec, attr: AttrLikeSpec): Option[CompilationProblem] = {
     getRepeatExprReference(spec, attr).flatMap(repeatExprRefAttr => {
       val existingName = repeatExprRefAttr.id.humanReadable
       val goodName = s"num_${attr.id.humanReadable}"
       if (existingName != goodName) {
+        // Report error at position where referenced attribute is defined.
+        // Add `id` for attributes in `seq`, do not add for instances
+        val path = repeatExprRefAttr match {
+          case _: InstanceSpec => repeatExprRefAttr.path
+          case _ => repeatExprRefAttr.path :+ "id"
+        }
         Some(StyleWarningRepeatExprNum(
           goodName,
           existingName,
           attr.id.humanReadable,
-          ProblemCoords(path = Some(repeatExprRefAttr.path ++ List("id")))
+          ProblemCoords(path = Some(path))
         ))
       } else {
         None