chore: remove strong-named key references and signing for .NET (#12632)

The benefits of strong-name signing assemblies are marginal at best, and it
turns out we actually weren't strong-name signing our assemblies anyway, making
all of this extra infrastructure unnecessary.

This removes the strong-name key (SNK) prebuild script, updates the buildspec
to remove the reference to it, and removes the linter rule that enforced the
strong-named assembly properties. Prior to removal, the rule was reversed and
used to update the package.json files.

This change will be accompanied by a change to our pipeline definition to
remove the references on that side.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: njlynch

buildspec.yaml

@@ -12,9 +12,6 @@ phases:
 
       # Install yarn if it wasn't already present in the image
       - yarn --version || npm -g install yarn
-  pre_build:
-    commands:
-      - /bin/bash ./fetch-dotnet-snk.sh
   build:
     commands:
       - 'if ${BUMP_CANDIDATE:-false}; then /bin/bash ./scripts/bump-candidate.sh; fi'

fetch-dotnet-snk.sh

@@ -10,8 +10,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.Alexa.Ask",
         "packageId": "Amazon.CDK.Alexa.Ask",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "java": {

packages/@aws-cdk/alexa-ask/package.json

@@ -16,8 +16,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AppDelivery",
         "packageId": "Amazon.CDK.AppDelivery",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "python": {

packages/@aws-cdk/app-delivery/package.json

@@ -17,8 +17,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.Assets",
         "packageId": "Amazon.CDK.Assets",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "python": {

packages/@aws-cdk/assets/package.json

@@ -10,8 +10,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AWS.AccessAnalyzer",
         "packageId": "Amazon.CDK.AWS.AccessAnalyzer",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "java": {

packages/@aws-cdk/aws-accessanalyzer/package.json

@@ -10,8 +10,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AWS.ACMPCA",
         "packageId": "Amazon.CDK.AWS.ACMPCA",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "java": {

packages/@aws-cdk/aws-acmpca/package.json

@@ -10,8 +10,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AWS.AmazonMQ",
         "packageId": "Amazon.CDK.AWS.AmazonMQ",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "java": {

packages/@aws-cdk/aws-amazonmq/package.json

@@ -10,8 +10,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AWS.Amplify",
         "packageId": "Amazon.CDK.AWS.Amplify",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "java": {

packages/@aws-cdk/aws-amplify/package.json

@@ -17,8 +17,6 @@
       "dotnet": {
         "namespace": "Amazon.CDK.AWS.APIGateway",
         "packageId": "Amazon.CDK.AWS.APIGateway",
-        "signAssembly": true,
-        "assemblyOriginatorKeyFile": "../../key.snk",
         "iconUrl": "https://raw.githubusercontent.com/aws/aws-cdk/master/logo/default-256-dark.png"
       },
       "python": {