GRAM: Support exclusive ranges in patterns (.. in if let and match arms)

Inclusive ranges in patterns use '...' (possibly also '..=' in the future).
Exclusive ranges in patterns use '..'

This feature is currently unstable and can be enabled with
 #![feature(exclusive_range_pattern)]

Author: kumbayo

src/main/grammars/RustParser.bnf

@@ -401,7 +401,7 @@ Pat ::= PatWild
       | PatStruct
       | PatEnum
       | PatIdent
-      | (PatConst !'...')
+      | (PatConst !('..' | '...'))
       | PatRange
       | PatUniq
 
@@ -427,7 +427,7 @@ private Pat_with_recover ::= Pat (',' | &(')' | ']' | '..'))
 private PatField_with_recover ::= PatField (',' | & '}')
 
 PatConst ::= PathExpr | LitExpr | &('-' LitExpr) UnaryExpr
-PatRange ::= PatConst '...' PatConst { pin = 2 }
+PatRange ::= PatConst ('..' | '...') PatConst { pin = 2 }
 
 PatTup ::= '(' SeqPat ')'
 PatVec ::= '[' SeqPat ']'

src/test/kotlin/org/rust/ide/formatter/RsFormatterTest.kt

@@ -307,10 +307,12 @@ class RsFormatterTest : RsFormatterTestBase() {
 
     fun `test unary minus in range patterns`() = doTextTest("""
         fn main() {
+            if let - 10 .. - 1 = - 8 {}
             if let - 10 ... - 1 = - 8 {}
         }
     """, """
         fn main() {
+            if let -10..-1 = -8 {}
             if let -10...-1 = -8 {}
         }
     """)

src/test/kotlin/org/rust/lang/core/type/RsNumericLiteralTypeInferenceTest.kt

@@ -414,7 +414,7 @@ class RsNumericLiteralTypeInferenceTest : RsTypificationTestBase() {
         }
     """)
 
-    fun `test unify match pattern range`() = testExpr("""
+    fun `test unify match pattern inclusive range`() = testExpr("""
         fn main() {
             match 0u8 {
                 0...1 => {},
@@ -424,6 +424,16 @@ class RsNumericLiteralTypeInferenceTest : RsTypificationTestBase() {
         }
     """)
 
+    fun `test unify match pattern exclusive range`() = testExpr("""
+        fn main() {
+            match 0u8 {
+                0..1 => {},
+              //^ u8
+                _ => {},
+            };
+        }
+    """)
+
     fun `test unify match pattern tuple`() = testExpr("""
         fn main() {
             match (0u8,) {