Add is_email_confirmed to users

[GJmelody]

Description of change

Add field is_email_confirmed to schema users. It indicates whether an invited user has accepted invitation and joined workspace

Sample slack API response
{
"id":"*********",
"name":"dummy_name",
"deleted":false,
"color":"757575",
"real_name":"dummy_name",
"tz":"America/Los_Angeles",
"tz_label":"Pacific Standard Time",
"tz_offset":-28800,
"profile":{},
"is_admin":false,
"is_owner":false,
"is_primary_owner":false,
"is_restricted":false,
"is_ultra_restricted":false,
"is_bot":false,
"is_app_user":false,
"updated":0,
"is_email_confirmed":false,
"who_can_share_contact_card":"EVERYONE"
}

Manual QA steps

N/A (not sure how to test)

Risks

This field maybe missing from certain API responses depending on the context of each Slack workspace

Rollback steps

• revert this branch

[cmerrick]

Hi @GJmelody, thanks for your contribution!

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[cmerrick]

You did it @GJmelody!

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[GJmelody]

@dwallace0723 could you help take a look at this PR? thank you so much!