Analysers from referenced projects does not affect referencee project

## Issue Description ##
Project `A` references Project `B`.
Project `B` has one (or more) analyser nuget package(s).

I expected the analyser to look for files in both projects. but I also have to add the nuget package to project A.

## Steps to Reproduce ##
Add an analyser to a project (Let's call it `B`)
On another project, reference project `B`

## Expected Behavior ##
Analyse both projects

## Actual Behavior ##
Only Project `B` files are analysed.

## Logs ##

### OmniSharp log ###
Post the output from Output-->OmniSharp log here

### C# log ###
Post the output from Output-->C# here

## Environment information ##

**VSCode version**: 1.42.1
**C# Extension**: 1.21.11

Dotnet Information
.NET Core SDK (reflecting any global.json):
Version: 3.1.100
Commit: cd82f021f4

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18362
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.1.100\

Host (useful for support):
Version: 3.1.0
Commit: 65f04fb6db

.NET Core SDKs installed:
2.2.401 [C:\Program Files\dotnet\sdk]
2.2.402 [C:\Program Files\dotnet\sdk]
3.1.100 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Visual Studio Code Extensions

|Extension|Author|Version|
|---|---|---|
|azds|azuredevspaces|2.0.220200218|
|azure-account|ms-vscode|0.8.8|
|csharp|ms-vscode|1.21.11|
|dotnet-test-explorer|formulahendry|0.7.1|
|EditorConfig|EditorConfig|0.14.4|
|php-debug|felixfbecker|1.13.0|
|php-intellisense|felixfbecker|2.3.14|
|postcss|ricard|2.0.0|
|powershell|ms-vscode|2020.1.0|
|prettier-vscode|esbenp|3.20.0|
|python|ms-python|2020.2.63990|
|remote-wsl|ms-vscode-remote|0.42.3|
|solidity|JuanBlanco|0.0.70|
|svelte-intellisense|ardenivanov|0.7.1|
|svelte-vscode|JamesBirtles|0.9.3|
|terraform|mauve|1.4.0|
|tslint-vue|prograhammer|1.5.6|
|twig|whatwedo|1.0.2|
|vetur|octref|0.23.0|
|vscode-aks-tools|ms-kubernetes-tools|0.0.4|
|vscode-docker|ms-azuretools|0.10.0|
|vscode-eslint|dbaeumer|2.0.15|
|vscode-firefox-debug|firefox-devtools|2.6.1|
|vscode-kubernetes-tools|ms-kubernetes-tools|1.0.9|
|vscode-php-getters-setters|phproberto|1.2.3|
|vscode-svelte-snippets|fivethree|0.3.0|
|vscode-typescript-tslint-plugin|ms-vscode|1.2.3|
|vscode-yaml|redhat|0.7.2|;