Bump version to 3.17.3

[chagong]

Bump version to 3.17.3 and update CHANGELOG.

Changes included in this release

Performance

• Batch BSP calls during import to reduce round-trips from ~4400 to 6 (Batch BSP calls during import to reduce round-trips from ~4400 to 6 #1791)
• Skip reloadWorkspace() when compile tasks are all UP-TO-DATE (build-server-for-gradle#222)

Fixed

• Suppress auto-build during BSP didChange to prevent infinite rebuild loop (fix: suppress auto-build during BSP didChange to prevent infinite rebuild loop #1794)
• Improve server connection stability and fix resource leaks (fix: improve server connection stability and fix resource leaks #1796)
• Fix log message taskId NPE error (fix: log message taskId NPE error #1769)
• Fix Gradle project test treeview refresh after running (fix: fix gradle project test treeview refresh after running #1766)
• Fix debug agent attaching to compilation tasks instead of target task (Fix debug agent attaching to compilation tasks instead of target task #1757)

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).