Sten Larsson

GH-48484: [GLib][Ruby] Add GArrowJoinOptions

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### Rationale for this change The `JoinOptions` class is not available in GLib/Ruby, and it is used together with the `binary_join_element_wise` compute function. ### What changes are included in this...

GH-48486: [GLib][Ruby] Add GArrowListFlattenOptions

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### Rationale for this change The `ListFlattenOptions` class is not available in GLib/Ruby, and it is used together with the `list_flatten` compute function. ### What changes are included in this...

### Describe the enhancement requested The `ListFlattenOptions` class is not available in GLib/Ruby, and it is used together with the `list_flatten` compute function. ### Component(s) GLib

### Describe the enhancement requested The `JoinOptions` class is not available in GLib/Ruby, and it is used together with the `binary_join_element_wise` compute function. ### Component(s) GLib

GH-41364: [GLib][Ruby] Allow passing thread pool to ExecutePlan

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### Rationale for this change Aggregators like `first` and `last` are unusable in Ruby because they don't work when the execution plan is executed using multiple threads. ### What changes...