Add support for placeholders and their substitutions in paths

[adellhk]

Using a string at DLD instance instantiation, users can configure one placeholder's replacement with that string

public BaseDeepLinkDelegate(
    List<? extends BaseRegistry> registries,
    String pathVariableReplacementValue
  ) {
    this.registries = registries;
    this.pathVariableReplacementValue = pathVariableReplacementValue;
  }

Given:

• @DeepLink("https://www.example.com/-replaceable-path-variable-/") -DeepLinkDelegate(registries, "obamaOs")

Then:

• DeepLinkDelegate.supportsUri("https://www.example.com/obamaOs/") == true

@rossbacher @BenSchwab

[adellhk]

closing in favor of https://github.com/airbnb/DeepLinkDispatch/pull/274