SI-9140 Allow deprecating current parameter name

Allow deprecatedName to specify the name of the parameter
it qualifies.

This tells the user, That's my name, don't wear it out.
I.e., don't use my name when calling me.

Use cases include: the name will change; normally a name
should be provided for a boolean, but not in this case
(perhaps because there is only one argument).

```
scala> def f(@deprecatedName('foo) bar: String) = bar.reverse
f: (bar: String)String

scala> f(foo = "hello")
<console>:9: warning: the parameter name foo has been deprecated. Use bar instead.
              f(foo = "hello")
                    ^
res0: String = olleh

scala> def g(@deprecatedName('foo) foo: String) = foo.reverse
g: (foo: String)String

scala> g(foo = "hello")
<console>:9: warning: naming parameter foo has been deprecated.
              g(foo = "hello")
                    ^
res1: String = olleh
```

1 files changed, 2 insertions, 0 deletions

diff --git a/test/files/neg/names-defaults-neg.scala b/test/files/neg/names-defaults-neg.scala
index 042f73708c..d11c9910a1 100644
--- a/test/files/neg/names-defaults-neg.scala
+++ b/test/files/neg/names-defaults-neg.scala
@@ -92,6 +92,8 @@ object Test extends App {
   def deprNam3(@deprecatedName('x) a: Int, @deprecatedName('y) b: Int) = a + b
   deprNam3(y = 10, b = 2)
 
+  def deprNam4(@deprecatedName('deprNam4Arg) deprNam4Arg: String) = 0
+  deprNam4(deprNam4Arg = null)
 
   // t3818
   def f3818(x: Int = 1, y: Int, z: Int = 1) = 0