Remove unnecesssary special cases for "#" syntax that's going away

All of these specialty nodes will be subsumed by
MacroExpansionExprSyntax or MacroExpansionDeclSyntax.

Author: DougGregor

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -1995,14 +1995,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundFileExprSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
-  override func visit(_ node: PoundLineExprSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: TypealiasDeclSyntax) -> SyntaxVisitorContinueKind {
     arrangeAttributeList(node.attributes)
 
@@ -2041,10 +2033,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundErrorDeclSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: SpecializeExprSyntax) -> SyntaxVisitorContinueKind {
     return .visitChildren
   }
@@ -2094,10 +2082,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundColumnExprSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: WildcardPatternSyntax) -> SyntaxVisitorContinueKind {
     return .visitChildren
   }
@@ -2131,10 +2115,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundWarningDeclSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: ExpressionPatternSyntax) -> SyntaxVisitorContinueKind {
     return .visitChildren
   }
@@ -2159,10 +2139,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundFunctionExprSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: StringLiteralExprSyntax) -> SyntaxVisitorContinueKind {
     if node.openQuote.tokenKind == .multilineStringQuote {
       // If it's a multiline string, the last segment of the literal will end with a newline and
@@ -2228,10 +2204,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PoundDsohandleExprSyntax) -> SyntaxVisitorContinueKind {
-    return .visitChildren
-  }
-
   override func visit(_ node: AccessPathComponentSyntax) -> SyntaxVisitorContinueKind {
     return .visitChildren
   }