Prior to this commit, the GraphQL schema assembled by the
auto-configuration would provide no option for disabling the field
introspection.
While this feature is essential for many tools (including GraphiQL),
some prefer disabling it because this allows clients to gather
information about types and schema easily. This commit introduces a new
`spring.graphql.schema.introspection.enabled` configuration property.
Because potential attackers can still gather this information and this
feature is a core concern in the GraphQL spec, introspection is enabled
by default for Spring Boot applications.
Closes gh-29248
