Add tests for appending values to sequence operation

idea/testData/debugger/sequence/exec/sequence/outs/plusArray.out

@@ -0,0 +1,38 @@
+LineBreakpoint created at PlusArray.kt:5
+Run Java
+Connected to the target VM
+PlusArray.kt:5
+listOf(1, 2, 3).asSequence()
+.plus(arrayOf(3, 4, 5))
+.count()
+plus
+    before: 1,3,5
+    after: 2,4,6,7,8,9
+count
+    before: 2,4,6,7,8,9
+    after: nothing
+mappings for plus
+  direct:
+    1 -> 2
+    3 -> 4
+    5 -> 6
+  reverse:
+    1 <- 2
+    3 <- 4
+    5 <- 6
+    nothing <- 7
+    nothing <- 8
+    nothing <- 9
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    6 -> nothing
+    7 -> nothing
+    8 -> nothing
+    9 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/outs/plusElement.out

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+LineBreakpoint created at PlusElement.kt:5
+Run Java
+Connected to the target VM
+PlusElement.kt:5
+sequenceOf(1, 2)
+.plusElement(10)
+.count()
+plusElement
+    before: 1,3
+    after: 2,4,5
+count
+    before: 2,4,5
+    after: nothing
+mappings for plusElement
+  direct:
+    1 -> 2
+    3 -> 4
+  reverse:
+    1 <- 2
+    3 <- 4
+    nothing <- 5
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    5 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/outs/plusSequence.out

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+LineBreakpoint created at PlusSequence.kt:5
+Run Java
+Connected to the target VM
+PlusSequence.kt:5
+sequenceOf(10, 20)
+.plus(sequenceOf(30, 40))
+.count()
+plus
+    before: 1,3
+    after: 2,4,5,6
+count
+    before: 2,4,5,6
+    after: nothing
+mappings for plus
+  direct:
+    1 -> 2
+    3 -> 4
+  reverse:
+    1 <- 2
+    3 <- 4
+    nothing <- 5
+    nothing <- 6
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    5 -> nothing
+    6 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/outs/plusSingle.out

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+LineBreakpoint created at PlusSingle.kt:5
+Run Java
+Connected to the target VM
+PlusSingle.kt:5
+sequenceOf(10, 20)
+.plus(30)
+.count()
+plus
+    before: 1,3
+    after: 2,4,5
+count
+    before: 2,4,5
+    after: nothing
+mappings for plus
+  direct:
+    1 -> 2
+    3 -> 4
+  reverse:
+    1 <- 2
+    3 <- 4
+    nothing <- 5
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    5 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/src/append/PlusArray.kt

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+package append
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  listOf(1, 2, 3).asSequence().plus(arrayOf(3, 4, 5)).count()
+}

idea/testData/debugger/sequence/exec/sequence/src/append/PlusElement.kt

@@ -0,0 +1,6 @@
+package append
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  sequenceOf(1, 2).plusElement(10).count()
+}

idea/testData/debugger/sequence/exec/sequence/src/append/PlusSequence.kt

@@ -0,0 +1,6 @@
+package append
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  sequenceOf(10, 20).plus(sequenceOf(30, 40)).count()
+}

idea/testData/debugger/sequence/exec/sequence/src/append/PlusSingle.kt

@@ -0,0 +1,6 @@
+package append
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  sequenceOf(10, 20).plus(30).count()
+}