Use int64 for StaticVirtualChannels

[olljanat]

Without this change building 32-bit binaries fails to error:

# github.com/tomatome/grdp/plugin
..\..\..\..\pkg\mod\github.com\olljanat\grdp@v0.0.0-20231109070701-045cbccd0693\plugin\channel.go:182:28: cannot use CHANNEL_OPTION_INITIALIZED | CHANNEL_OPTION_ENCRYPT_RDP | CHANNEL_OPTION_COMPRESS_RDP | CHANNEL_OPTION_SHOW_PROTOCOL (untyped int constant 3231711232) as int value in map literal (overflows)
..\..\..\..\pkg\mod\github.com\olljanat\grdp@v0.0.0-20231109070701-045cbccd0693\plugin\channel.go:184:26: cannot use CHANNEL_OPTION_INITIALIZED | CHANNEL_OPTION_ENCRYPT_RDP | CHANNEL_OPTION_COMPRESS_RDP (untyped int constant 3229614080) as int value in map literal (overflows)
..\..\..\..\pkg\mod\github.com\olljanat\grdp@v0.0.0-20231109070701-045cbccd0693\plugin\channel.go:185:27: cannot use CHANNEL_OPTION_INITIALIZED | CHANNEL_OPTION_ENCRYPT_RDP | CHANNEL_OPTION_COMPRESS_RDP | CHANNEL_OPTION_SHOW_PROTOCOL (untyped int constant 3231711232) as int value in map literal (overflows)
..\..\..\..\pkg\mod\github.com\olljanat\grdp@v0.0.0-20231109070701-045cbccd0693\plugin\channel.go:187:25: cannot use CHANNEL_OPTION_INITIALIZED | CHANNEL_OPTION_ENCRYPT_RDP | CHANNEL_OPTION_COMPRESS_RDP | CHANNEL_OPTION_SHOW_PROTOCOL (untyped int constant 3231711232) as int value in map literal (overflows)