Remove obsolete types and members inclusive prior v0.15.0

[YevgeniyShunevych]

Remove constructor of WaitForElementAttribute:

[Obsolete("Use another constructor that uses 'Until' type instead of 'WaitUntil'.")] // Obsolete since v0.15.0.
public WaitForElementAttribute(WaitBy waitBy, string selector, WaitUntil until = WaitUntil.MissingOrHidden, TriggerEvents on = TriggerEvents.AfterClick, TriggerPriority priority = TriggerPriority.Medium)

Remove method of AtataContext:

[Obsolete("Use Configure() instead.")] // Obsolete since v0.14.0.
public static AtataContextBuilder Build();

Remove method of AtataContextBuilder:

[Obsolete("Use Build() instead.")] // Obsolete since v0.14.0.
public void SetUp();

Remove method of IDataProvider<out TData, TOwner>:

[Obsolete("Use Value instead.")]
TData Get();

Remove WaitUntil enum:

[Obsolete("Use Until instead.")] // Obsolete since v0.15.0.
public enum WaitUntil