Add a 'Decode as' option in 'Export Messages' dialog

[v-xianya]

Storage Explorer Version: 1.37.0-dev (103) Build Number: 20250109.1 Branch: main Platform/OS: Windows 11/Windows11/Linux Ubuntu 22.04/MacOS Sequoia 15.2(Apple M1 Pro) Architecture: x64/arm64/x64/arm64 How Found: Exploratory testing Regression From: Not a regression

Steps to Reproduce

1. Expand one storage account -> Queues.
2. Create a queue -> Click 'Export'.
3. The export message dialog appears.

Expected Experience

It is better to add an option like 'Decode as' to let user select the format in which they want to export the message text.

Actual Experience

There is no such option.

Additional Context

For the queue like this: The content of the export csv file as below:

[craxal]

Let's wait for some user feedback before committing to this.