Define and implement command line parsing with Options struct (#1984)

* Define Options struct, defaults and CLI flags

Signed-off-by: Etai Lev Ran <[email protected]>

* move flags and their validation to options.go

Signed-off-by: Etai Lev Ran <[email protected]>

* move options to pkg/epp/server, set endpoint ports as []int

Signed-off-by: Etai Lev Ran <[email protected]>

* call correct package Parse()

Signed-off-by: Etai Lev Ran <[email protected]>

* remove deprecation handler, add options Complete() and Validate() after pflag.Parse()

Signed-off-by: Etai Lev Ran <[email protected]>

* move constants to options.go

Signed-off-by: Etai Lev Ran <[email protected]>

* move zap logging options to options.go

Signed-off-by: Etai Lev Ran <[email protected]>

* add endpoint port tests

Signed-off-by: Etai Lev Ran <[email protected]>

* import grouping

Signed-off-by: Etai Lev Ran <[email protected]>

* move flag printing after validation

Signed-off-by: Etai Lev Ran <[email protected]>

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Signed-off-by: Etai Lev Ran <[email protected]>

Author: elevran