collab: Add ability to add tax ID during Stripe Checkout (#34246)

### 1. **Added Tax ID Collection Types**
- Created a new `StripeTaxIdCollection` struct with an `enabled` field
- Added `tax_id_collection` field to `StripeCreateCheckoutSessionParams`

### 2. **Updated the Stripe Client Interface**
- Modified the real Stripe client to handle tax ID collection conversion
- Updated the fake Stripe client for testing purposes
- Added proper imports across all affected files

### 3. **Enabled Tax ID Collection in Checkout Sessions**
- Both `checkout_with_zed_pro` and `checkout_with_zed_pro_trial` methods
now enable tax ID collection
- The implementation correctly sets `tax_id_collection.enabled = true`
for all checkout sessions

### 4. **Key Implementation Details**
- Tax ID collection will be shown to new customers and existing
customers without tax IDs
- Collected tax IDs will be automatically saved to the customer's
`tax_ids` array in Stripe
- Business names will be saved to the customer's `name` property
- The existing `customer_update.name = auto` setting ensures
compatibility with tax ID collection

Release Notes:

- N/A

crates/collab/src/stripe_client.rs

@@ -190,6 +190,7 @@ pub struct StripeCreateCheckoutSessionParams<'a> {
     pub success_url: Option<&'a str>,
     pub billing_address_collection: Option<StripeBillingAddressCollection>,
     pub customer_update: Option<StripeCustomerUpdate>,
+    pub tax_id_collection: Option<StripeTaxIdCollection>,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -218,6 +219,11 @@ pub struct StripeCreateCheckoutSessionSubscriptionData {
     pub trial_settings: Option<StripeSubscriptionTrialSettings>,
 }
 
+#[derive(Debug, PartialEq, Clone)]
+pub struct StripeTaxIdCollection {
+    pub enabled: bool,
+}
+
 #[derive(Debug)]
 pub struct StripeCheckoutSession {
     pub url: Option<String>,