Add sample application for ScalarDB Cluster .NET Client SDK (LINQ)

[Dima-X]

Description

This PR adds sample application for ScalarDB Cluster .NET Client SDK that uses LINQ.
This is a LINQ version of #77

Related issues and/or PRs

https://github.com/scalar-labs/docs-internal-scalardb/pull/1062

Changes made

• sample added to scalardb-dotnet-samples/scalardb-cluster-linq-sample
• Visual Studio specific exceptions were added to .gitignore

Checklist

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

[brfrn169]

LGTM! Thank you!

[komamitsu]

@feeblefakie @brfrn169 @Torch3333 I added a small fix to throw the last exception when the retry is over 2faa2e9. PTAL just in case.

[komamitsu]

LGTM! 👍

[Torch3333]

LGTM, thank you!

[kota2and3kan]

LGTM! Thank you!

---

FYI: I was able to run this sample application in my local environment as follows:

$ dotnet run PlaceOrder 1 3:1,4:1
{
  "order_id": "ab391787-302d-446d-8f85-429432df4dd9"
}