fix: Remove appStartMillis and appStartEndMillis getters and make getAppStartTime public instead (#1629)

Author: jennmueng

sentry-android-core/api/sentry-android-core.api

@@ -35,8 +35,7 @@ public final class io/sentry/android/core/AppLifecycleIntegration : io/sentry/In
 }
 
 public final class io/sentry/android/core/AppStartState {
-	public fun getAppStartEndMillis ()Ljava/lang/Long;
-	public fun getAppStartMillis ()Ljava/lang/Long;
+	public fun getAppStartTime ()Ljava/util/Date;
 	public static fun getInstance ()Lio/sentry/android/core/AppStartState;
 	public fun isColdStart ()Z
 }

sentry-android-core/src/main/java/io/sentry/android/core/AppStartState.java

@@ -60,7 +60,7 @@ synchronized void setColdStart(final boolean coldStart) {
   }
 
   @Nullable
-  Date getAppStartTime() {
+  public Date getAppStartTime() {
     return appStartTime;
   }
 
@@ -72,12 +72,4 @@ synchronized void setAppStartTime(final long appStartMillis, final @NotNull Date
     this.appStartTime = appStartTime;
     this.appStartMillis = appStartMillis;
   }
-
-  public @Nullable Long getAppStartMillis() {
-    return appStartMillis;
-  }
-
-  public @Nullable Long getAppStartEndMillis() {
-    return appStartEndMillis;
-  }
 }