feat(bigtable): Add ignore_warnings flag to SetGcPolicy

[andre-sampaio]

This exposes the flag ignore_warnings for ModifyColumnFamiliesRequest.

[bhshkh]

Please create an issue for this pull request describing the problem

[andre-sampaio]

resolves #9469

[bhshkh]

If and when more fields are added to ModifyColumnFamiliesRequest, we will have to create more methods to allow setting those. Adding SetGCPolicyWithOptions which takes an options struct (with ignorewarnings bool field) instead of SetGCPolicyIgnoreWarnings would be a better option for future extendability.

[bhshkh]

If and when more fields are added to ModifyColumnFamiliesRequest, we will have to create more methods to allow setting those. Adding SetGCPolicyWithOptions which takes an options struct (with ignorewarnings bool field) instead of SetGCPolicyIgnoreWarnings would be a better option for future extendability.

Added these changes

[gkevinzheng]

@bhshkh Don't we usually have GCPolicyOptions be an interface with a set function and different functions that return different structs? Why aren't we using that pattern here?

[andre-sampaio]

Thank you for adding those changes, @bhshkh. Agree that it is better that way for extensibility

[andre-sampaio]

@bhshkh are there more concerns regarding this change?

[bhshkh]

@bhshkh Don't we usually have GCPolicyOptions be an interface with a set function and different functions that return different structs? Why aren't we using that pattern here?

Modified the code to match the pattern:

google-cloud-go/spanner/value.go

Lines 3853 to 3872 in 949242c

	// decodeSetting contains all the settings for decoding from spanner struct
	type decodeSetting struct {
	Lenient bool
	}
	// DecodeOptions is the interface to change decode struct settings
	type DecodeOptions interface {
	Apply(s *decodeSetting)
	}
	type withLenient struct{ lenient bool }
	func (w withLenient) Apply(s *decodeSetting) {
	s.Lenient = w.lenient
	}
	// WithLenient returns a DecodeOptions that allows decoding into a struct with missing fields in database.
	func WithLenient() DecodeOptions {
	return withLenient{lenient: true}
	}