A button "resume download" is needed to finish-up template downloading under images/Templates/zones

##### ISSUE TYPE

* Improvement Request
* Enhancement Request

##### COMPONENT NAME

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UI
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##### CLOUDSTACK VERSION

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4.17.0.1
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##### CONFIGURATION

Advanced Networking

##### OS / ENVIRONMENT

RHEL-7.9

##### SUMMARY

While a template is being uploaded/pushed to a specific zone due to network issues the image/template was not fully downloaded onto that zone. Currently the download percentage is showing as 31%, and even though the management server was bounced yet the download is not getting completed and am looking for a button to resume the download but there is none.

##### STEPS TO REPRODUCE

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step1: Navigate to images/templates and click "Register template from URL"
step2: Fill-up the form to download the template to the desired zone and click OK
step3: While the template is being downloaded - due to network outages or the apache server where qcow2 templates are kept suddenly goes down this will interrupt the template downloading to a specific zone(s).
step4: Once the network outage is resolved, the user should be in a position to "resume download" on images/Templates/zones tab which is NOT available at the moment, hence creating this enhancement request
~~~

##### EXPECTED RESULTS

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As soon as the network issue is resolved, the user should be able to resume the template download by clicking "Resume Download" button.
~~~

##### ACTUAL RESULTS

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there is no button to resume the template download;
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從 images/Templates/zones 分頁開始，按照列出的步驟重現中斷的下載，包括網路中斷。檢視現有的範本下載流程，並決定應如何提供恢復下載的功能；完成的標準是使用者在網路恢復後可以點擊 "Resume Download"，且範本下載完成。

由索引模型根據 Issue 內容生成。