Support setting file sync ignore patterns via the UI

[ethanndickson]

A Synchronization CreateRequest allows specifying a configuration for alpha, beta, or both simultaneously.
These configurations include the following fields:

    // Ignore configuration parameters (fields 31-60).

    // IgnoreSyntax specifies the syntax and semantics to use for ignores.
    // NOTE: This field is out of order due to the historical order in which it
    // was added.
    ignore.Syntax ignoreSyntax = 34;

    // DefaultIgnores specifies the ignore patterns brought in from the global
    // configuration.
    // DEPRECATED: This field is no longer used when loading from global
    // configuration. Instead, ignores provided by global configuration are
    // simply merged into the ignore list of the main configuration. However,
    // older sessions still use this field.
    repeated string defaultIgnores = 31;

    // Ignores specifies the ignore patterns brought in from the create request.
    repeated string ignores = 32;

    // IgnoreVCSMode specifies the VCS ignore mode that should be used in
    // synchronization.
    ignore.IgnoreVCSMode ignoreVCSMode = 33;

We'll need to expose these synchronization configuration options via the UI.