Rust: Fix bad join in fileImport

Before
```
Evaluated relational algebra for predicate PathResolution::fileImport/2#d9e57816@c790f609 with tuple counts:
           241   ~0%    {3} r1 = JOIN `_Locatable::Locatable.getFile/0#dispred#f7e24934_PathResolution::isSourceFile/1#803de032#shared` WITH `FileSystem::Folder::Append<PathResolution::shouldAppend>::append/2#beb8f79a_201#join_rhs` ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.1
           291   ~0%    {2}    | JOIN WITH `PathResolution::pathAttrImport/3#88463ffa_021#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.2

         14978   ~8%    {2} r2 = SCAN `PathResolution::modImport0/3#03cccf2a` OUTPUT In.0, In.1
         14978   ~8%    {2}    | STREAM DEDUP

         14392   ~9%    {2} r3 = r2 AND NOT `PathResolution::modImportNested/3#991244df_0#antijoin_rhs`(FIRST 1)
         14392   ~0%    {3}    | JOIN WITH `PathResolution::modImport0/3#03cccf2a` ON FIRST 2 OUTPUT Lhs.1, Rhs.2, Lhs.0
         14355   ~0%    {4}    | JOIN WITH `PathResolution::fileModule/3#d6c6ceef#fbf_120#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.0, Lhs.1, Lhs.2

         14978   ~0%    {2} r4 = JOIN r2 WITH `PathResolution::modImport0/3#03cccf2a` ON FIRST 2 OUTPUT Lhs.1, Lhs.0
        329862   ~0%    {5}    | JOIN WITH `PathResolution::fileModule/3#d6c6ceef#fbf_102#join_rhs` ON FIRST 1 OUTPUT Lhs.1, Lhs.1, Rhs.2, Lhs.0, Rhs.1
           577   ~3%    {4}    | JOIN WITH `PathResolution::modImportNestedLookup/3#6cc4b913#ffb` ON FIRST 3 OUTPUT Lhs.4, Lhs.3, Lhs.2, Lhs.0

         14932   ~0%    {4} r5 = r3 UNION r4
         14932   ~0%    {2}    | JOIN WITH `PathResolution::fileModule/3#d6c6ceef#fbf` ON FIRST 3 OUTPUT Lhs.0, Lhs.3
         14932   ~0%    {2}    | JOIN WITH `PathResolution::isSourceFile/1#803de032` ON FIRST 1 OUTPUT Lhs.1, Lhs.0

         15223   ~0%    {2} r6 = r1 UNION r5
                        return r6
```

Afer
```
Evaluated relational algebra for predicate PathResolution::fileImport/2#d9e57816@007bd81i with tuple counts:
          241   ~0%    {3} r1 = JOIN `_Locatable::Locatable.getFile/0#dispred#f7e24934_PathResolution::isSourceFile/1#803de032#shared` WITH `FileSystem::Folder::Append<PathResolution::shouldAppend>::append/2#beb8f79a_201#join_rhs` ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.1
          291   ~0%    {2}    | JOIN WITH `PathResolution::pathAttrImport/3#88463ffa_021#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.2

        14978   ~8%    {2} r2 = SCAN `PathResolution::modImport0/3#03cccf2a` OUTPUT In.0, In.1
        14978   ~8%    {2}    | STREAM DEDUP

        14392   ~9%    {2} r3 = r2 AND NOT `PathResolution::modImportNested/3#991244df_0#antijoin_rhs`(FIRST 1)
        14392   ~0%    {3}    | JOIN WITH `PathResolution::modImport0/3#03cccf2a` ON FIRST 2 OUTPUT Lhs.1, Rhs.2, Lhs.0

        14978   ~9%    {3} r4 = JOIN r2 WITH `PathResolution::modImport0/3#03cccf2a` ON FIRST 2 OUTPUT Lhs.0, Lhs.0, Lhs.1
          577   ~0%    {3}    | JOIN WITH `PathResolution::modImportNestedLookup/3#6cc4b913#ffb` ON FIRST 2 OUTPUT Lhs.2, Rhs.2, Lhs.0

        14969   ~1%    {3} r5 = r3 UNION r4
        14932   ~0%    {2}    | JOIN WITH `PathResolution::fileModule/3#d6c6ceef_120#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.2
        14932   ~0%    {2}    | JOIN WITH `PathResolution::isSourceFile/1#803de032` ON FIRST 1 OUTPUT Lhs.1, Lhs.0

        15223   ~0%    {2} r6 = r1 UNION r5
                       return r6
```

Author: hvitved

rust/ql/lib/codeql/rust/internal/PathResolution.qll

@@ -988,6 +988,7 @@ private predicate sourceFileEdge(SourceFile f, string name, ItemNode item) {
 }
 
 /** Holds if `f` is available as `mod name;` inside `folder`. */
+pragma[nomagic]
 private predicate fileModule(SourceFile f, string name, Folder folder) {
   exists(File file | file = f.getFile() |
     file.getBaseName() = name + ".rs" and
@@ -1002,6 +1003,12 @@ private predicate fileModule(SourceFile f, string name, Folder folder) {
   )
 }
 
+bindingset[name, folder]
+pragma[inline_late]
+private predicate fileModuleInlineLate(SourceFile f, string name, Folder folder) {
+  fileModule(f, name, folder)
+}
+
 /**
  * Gets the `Meta` of the module `m`'s [path attribute][1].
  *
@@ -1084,7 +1091,7 @@ pragma[nomagic]
 predicate fileImport(Module m, SourceFile f) {
   exists(string name, Folder parent |
     modImport0(m, name, _) and
-    fileModule(f, name, parent)
+    fileModuleInlineLate(f, name, parent)
   |
     // `m` is not inside a nested module
     modImport0(m, name, parent) and