Move ftp file server code to common pkg #34727

Job	Run time
Check whether tests need to be run based on diff	21s
Verify docs and spelling	29s
Integration test	5m 51s
Unit test (ubuntu-latest)	7m 30s
Build Antrea and antctl binaries	12m 40s
Golangci-lint (macos-latest)	8m 12s
Golangci-lint (ubuntu-latest)	9m 5s
Unit test (windows-2022)	13m 0s
Go benchmark test	5m 13s
Check tidy, code generation and manifest	4m 17s
Build Antrea Windows binaries	2m 12s
	1h 8m 50s

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