SOLR-17949: Fix licenses and add changelog entry

- Changed msal4j-LICENSE-ASL.txt to msal4j-LICENSE-MIT.txt
- Changed azure-LICENSE-ASL.txt to azure-LICENSE-MIT.txt
- Removed msal4j-NOTICE.txt (MIT license does not require NOTICE)
- Removed azure-NOTICE.txt (MIT license does not require NOTICE)
- Verified all dependencies:
  * MSAL4J (2 libs): MIT licensed
  * Azure SDK (8 libs): MIT licensed
  * Reactor (3 libs): Apache 2.0 (correct)
  * Netty (30+ libs): Apache 2.0 (correct)
- Added changelog entry for the new Azure Blob Storage backup repository module

Author: prateeksinghalgit

changelog/unreleased/SOLR-17949-azure-blob-repository.yml

@@ -0,0 +1,11 @@
+# See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
+title: Add Azure Blob Storage backup repository module
+type: added
+authors:
+  - name: Prateek Singhal
+description: |
+  Added AzureBlobBackupRepository module for backing up and restoring Solr collections to Azure Blob Storage.
+  Supports multiple authentication methods: connection string, account name + key, SAS token, and Azure Identity (service principal, managed identity).
+links:
+  - name: SOLR-17949
+    url: https://issues.apache.org/jira/browse/SOLR-17949

solr/licenses/azure-LICENSE-ASL.txt

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Microsoft
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+