Improve patches (#2057)

- Break large diffs apart into logical changes.
- Improve context in message of each patch.
- Remove a few obsolete patches.

## Remove patch "Add parse & validate code
This seems to be left-over from a bad merge from:
- postgres:
hashicorp/terraform-provider-azurerm#17625
- compute:
hashicorp/terraform-provider-azurerm@789e659
- privatedns:
hashicorp/terraform-provider-azurerm#16858

## Drop test modifications

The tests work fine without our patches

## Drop FunctionApp client_affinity_enabled field handling

This field doesn't exist in the schema or the docs. This was removed
upstream in
hashicorp/terraform-provider-azurerm@fb47e34

## Drop patch: Limit network_security_rule
*_application_security_group_ids to 1

Replace with setting MaxItemsOne in the resources.go

## Exported patch of the diff between the computed upstream changes 

[upstream-f045f3f-New
changes.patch](https://github.com/pulumi/pulumi-azure/files/15404929/upstream-f045f3f-New.changes.patch)

patches/0001-Client-options.patch → patches/0001-Set-user-agent-in-client-options.patch

@@ -1,8 +1,9 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: aq17 <aqiu@pulumi.com>
 Date: Thu, 25 May 2023 10:33:38 -0700
-Subject: [PATCH] Client-options
+Subject: [PATCH] Set user agent in client options
 
+Use Pulumi-specific user agent which includes the current provider version number.
 
 diff --git a/internal/common/client_options.go b/internal/common/client_options.go
 index 4b2d3a5a5b..451c27f7f2 100644

patches/0008-expose-provider.patch → patches/0002-Expose-provider-via-shim.patch

@@ -1,8 +1,9 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: aq17 <aqiu@pulumi.com>
 Date: Thu, 25 May 2023 10:33:39 -0700
-Subject: [PATCH] expose-provider
+Subject: [PATCH] Expose provider via shim
 
+Add shim module containing a public method which constructs a new instance of the internal provider class so we're able to access the provider class directly in order to bridge it.
 
 diff --git a/shim/shim.go b/shim/shim.go
 new file mode 100644