skip flag verification for arguments, only verify flags

[#84317640]

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>
skip validating negative integer when it is a value to another flag

[finishes #84317640]

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>
improve help text for install-plugin

[finishes #84601290]

Signed-off-by: Simon Leung <leungs@us.ibm.com>