[code-selection] Selection issues involving enhanced switch

Regarding #2299 @srikanth-sankaran suggested to compare codeComplete() with codeSelect().

Within test cases fixed in #2391 I found a few problems of codeSelect() itself:

```java
public void foo(java.io.Serializable o) {
switch(o) {
case Person(var name, var age) : {
/*here*/name
}
}
}
```
selecting on "name" (incomplete statement) produces (via RecoveredElement.updateParseTree()) this method AST (the second "case" is wrong):
```
public void foo(java.io.Serializable o) {
{
{
switch (o) {
case Person(var name, var age) :
case :
}
}
}
}
```

Same problem also in switch *expression*.

With tricky nesting involved:
```java
public void foo(java.io.Serializable o) {
switch(o) {
case Person(var name, var age): {
col.stream().filter(el -> el.equals(/*here*/name))
}
};
}
```
AST drops all added context (is it irrelevant? so dropping might be by intention?):
```
public void foo(java.io.Serializable o) {
{
{
switch (o) {
case Person(var name, var age) :
case :
}
}
}
}
```

And the trickiest for new tests:
```java
public void foo(List col) {
col.stream().filter(el -> {
switch(el) {
case Person(var name, var age): {
/*here*/name
}
};
})
}
```
gives
```
public void foo(List col) {
}
```
ups...