Add changelog v1.2.9

doc/changelog/changelog_v1.2.9.md

+# Version v1.2.9
+
+## My operations
+- Avoid duplicated transaction, and refresh issue - Fix [#780](https://git.duniter.org/clients/cesium-grp/cesium/issues/780)
+- Add icon on each divider 
+
+## My wallets
+- Display the total balance of wallets
+- Show the default (main) wallet 
+- Better wallets refresh animation
+- Fix: wallet list can be lost when view not fully loaded - Fix [#782](https://git.duniter.org/clients/cesium-grp/cesium/issues/782) 
+- Fix: Avoid multiple error when failed - Fix [#776](https://git.duniter.org/clients/cesium-grp/cesium/issues/776) 
+
+## Cesium+ features
+
+### Messages
+- Fix sending message from a secondary wallet - fix [#784](https://git.duniter.org/clients/cesium-grp/cesium/issues/784) 
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