feat(tax): adds getItemTaxLines (#6440)

**What**
- Selects the correct tax line for an item given a calculation context.

**For later PR**
- Consider optimizations. Some thoughts:
  - Even with global sales the number of rates in the DB is not likely to grow beyond ~1000.
  - Can large orders with hundreds of items optimize somehow?
  - Does it make sense to write a custom SQL query to do this?
- Support combined rate.

**Test cases covered**
The selection of tax rates take the following priority:

1. specific product rules - province
2. specific product type rules - province
3. default province rules
4. specific product rules - country
5. specific product type rules - country
6. default country rules

There are test cases for each of them under the following data seed structure:

### **US** 
- **Default Rate**: 2%
- **Sub-Regions**
  - CA 
    - Default Rate: 5%
    - Overrides
      - Reduced rate (for 3 product ids): 3%
      - Reduced rate (for product type): 1%
  - NY 
    - Default rate: 6%
  - FL 
    - Default rate: 4%
- **Overrides**
  - None

### **Denmark** 
- **Default rate:** 25% 
- **Sub-Regions**
  - None
- **Overrides**
  -  None

### **Germany** 
- **Default Rate:** 19%
- **Sub-Regions**
  - None
- **Overrides:**
  - Reduced Rate (for product type) - 7%

### **Canada** 
- **Default rate**: 5%
- **Sub-Regions**
  - QC 
    - Default rate: 2%
    - Overrides:
      - Reduced rate (for same product type as country reduced rate): 1%
  - BC 
    - Default rate: 2%
- **Overrides**
  - Reduced rate (for product id) - 3%
  - Reduced rate (for product type) - 3.5%

packages/tax/integration-tests/utils/database.ts

@@ -1,12 +0,0 @@
-import { TestDatabaseUtils } from "medusa-test-utils"
-
-import * as Models from "@models"
-
-const mikroOrmEntities = Models as unknown as any[]
-
-export const MikroOrmWrapper = TestDatabaseUtils.getMikroOrmWrapper({
-  mikroOrmEntities,
-  schema: process.env.MEDUSA_ORDER_DB_SCHEMA,
-})
-
-export const DB_URL = TestDatabaseUtils.getDatabaseURL()

packages/tax/integration-tests/utils/get-init-module-config.ts

@@ -1,33 +0,0 @@
-import { Modules, ModulesDefinition } from "@medusajs/modules-sdk"
-
-import { DB_URL } from "./database"
-
-export function getInitModuleConfig() {
-  const moduleOptions = {
-    defaultAdapterOptions: {
-      database: {
-        clientUrl: DB_URL,
-        schema: process.env.MEDUSA_TAX_DB_SCHEMA,
-      },
-    },
-  }
-
-  const injectedDependencies = {}
-
-  const modulesConfig_ = {
-    [Modules.TAX]: {
-      definition: ModulesDefinition[Modules.TAX],
-      options: moduleOptions,
-    },
-  }
-
-  return {
-    injectedDependencies,
-    modulesConfig: modulesConfig_,
-    databaseConfig: {
-      clientUrl: DB_URL,
-      schema: process.env.MEDUSA_TAX_DB_SCHEMA,
-    },
-    joinerConfig: [],
-  }
-}

packages/tax/integration-tests/utils/index.ts

@@ -1,2 +0,0 @@
-export * from "./database"
-export * from "./get-init-module-config"