fix: address inconsistencies in SKU property case-sensitivity string checks

[CustardTart32]

This PR addresses inconsistencies in case-sensitivity when matching SKU capabilities. Previously, some functions used case-sensitive string matches whilst other functions used case-insensitive matches for SKU capability names.

[HuShaoRu]

in (v1) sku.go restriction.Type (line 349,373,476,539) and func MemberOf (line 579),
in v2/sku.go restriction.Type (line 319,339,438,500) and func MemberOf (line 541) are still case-sensitive. is it expected?

[matthchr]

Generally LGTM, but agree with @HuShaoRu you should fix the other comparisons as well.

[CustardTart32]

Pushed a comment to add a case-insensitive check for the MemberOf function. It should be fine to leave the examples provided by Shaoru as is. The restriction type checks are strict equality checks on two enum values rather than two arbitrary string values.

// ResourceSKURestrictionsType - The type of restrictions.
type ResourceSKURestrictionsType string

const (
	ResourceSKURestrictionsTypeLocation ResourceSKURestrictionsType = "Location"
	ResourceSKURestrictionsTypeZone     ResourceSKURestrictionsType = "Zone"
)