Support for transient data

### User Story Description

As a user I want to be able to load transient datasets and control the time step displayed.

Currently unsupported in AVZ (unofficially).

Note that currently we have the request only for one time set. So the animation control should work only on one timeset. It is in theory possible that in the future we will have requests to support multiple timesets in the same model (think about animated streamlines on a transient model), but it currently isn't needed

### Acceptance Criteria

Launch a session of VISOR. Load a transient dataset. The VISOR session shows a time display with the option to move between timesteps and play the entire time sequence.

Go to a specific timestep. Save a state file. In a new session of VISOR, load that state file. You are at the correct timestep.

### Additional Links

_No response_

### Requires new or update to third party ? If "yes" add the name(s) and the version(s) of the Third Party Software.

No

### Name and Version for Third Parties

_No response_

首先追蹤 VISOR 工作階段啟動、瞬態資料集載入、動畫控制項，以及狀態檔案儲存／載入行為。載入一個瞬態 timeset，在其時間步之間移動並播放，然後在相同時間步重新開啟已儲存的狀態，以驗證結果。

由索引模型根據 Issue 內容生成。