Expose BlobsTranscriptStore containerClient constructor

[joetossell]

Is your feature request related to a problem? Please describe.
Would like to use the aspire constructed container client but the BlobsTranscriptStore constructor accepting BlobContainerClient is internal. This is a similar issue to #393 which was resolved by making the relevant constructor public.

Describe the solution you'd like
Make the BlobsTranscriptStore internal constructor accepting BlobContainerClient public, as was done for BlobsStorage in #393

See:

Agents-for-net/src/libraries/Storage/Microsoft.Agents.Storage.Transcript/BlobsTranscriptStore.cs

Line 146 in 5bb2fa6

internal BlobsTranscriptStore(BlobContainerClient containerClient, JsonSerializerOptions jsonSerializer = null)

Describe alternatives you've considered
Vendoring the class

Additional context
Add any other context or screenshots about the feature request here.