Move precedingJoinState from EscapeSequenceParser to InputHandler

This allows InputHandler._parser to be IEscapeSequenceParser
rather than EscapeSequenceParser.

src/common/parser/EscapeSequenceParser.ts

@@ -231,9 +231,6 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
   public initialState: number;
   public currentState: number;
   public precedingCodepoint: number;
-  // Cached result of getJoinProperties(..., precedingCodepoint).
-  // Only valid if precedingCodepoint !== 0
-  public precedingJoinState: number = -1; // UnicodeJoinProperties
 
   // buffers over several parse calls
   protected _params: Params;