add blob content contribute role to backend (#206)

## Purpose
<!-- Describe the intention of the changes being proposed. What problem
does it solve or functionality does it add? -->
* ...

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[ ] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:
```

## How to Test
*  Get the code

```
git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install
```

* Test the code
<!-- Add steps to run the tests suite and/or manually test -->
```
```

## What to Check
Verify that the following are valid
* ...

## Other Information
<!-- Add any other helpful information that may be needed here. -->

infra/main.bicep

@@ -466,6 +466,16 @@ module storageRoleBackend 'core/security/role.bicep' = {
   }
 }
 
+module storageContribRoleBackend 'core/security/role.bicep' = {
+  scope: storageResourceGroup
+  name: 'storage-contribrole-backend'
+  params: {
+    principalId: web.outputs.SERVICE_WEB_IDENTITY_PRINCIPAL_ID
+    roleDefinitionId: 'ba92f5b4-2d11-453d-a403-e96b0029c9fe'
+    principalType: 'ServicePrincipal'
+  }
+}
+
 module searchRoleBackend 'core/security/role.bicep' = {
   scope: searchServiceResourceGroup
   name: 'search-role-backend'