[GLib] Use property to keep GArrowDataType passed in garrow_field_new()

[asfimport]

Reporter: Yosuke Shiro / @shiro615
Assignee: Yosuke Shiro / @shiro615

PRs and other links:

• GitHub Pull Request #3322

_{Note: This issue was originally created as ARROW-4168. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 3322
#3322