Making item request option triggers public

[j82w]

Pull Request Template

Description

Currently item request options pre/post triggers are internal which prevents users from running triggers on item operations. This was a missed because the properties do exist, but are internal. So all the test have access to the property.

ItemRequestOptions options = new ItemRequestOptions
{
	PreTriggers = new List<string>()
	{
		"preTrigger"
	},

	PostTriggers = new List<string>()
	{
		"postTrigger"
	}
};

Testing

Unit tests already exist:
CosmosClientResourceUnitTests.ValidateItemRequestOptions

Type of change

Please delete options that are not relevant.

• [x ] New feature (non-breaking change which adds functionality)

Closing issues

Put closes #556

[kirankumarkolli]

Please add examples and contract changes to issue.

[kirankumarkolli]

Are there UT covering both of them?

[kirankumarkolli]

ChangeLog update please