Update copyright and license headers (#6134)

Based on standard practices, we need to have a copyright and license notice at the top of each source file. Removed existing copyrights and updated/added copyright notices for .h, .cpp, .cs, .ps1, and .psm1 files.

Updated module manifests for consistency to have Author = "PowerShell" and Company = "Microsoft Corporation". Removed multiple line breaks.

Separate PR coming to update contribution document for new source files: #6140

Manually reviewed each change.

Fix #6073

test/powershell/engine/Module/assets/testmodulerunspace/NestedRequiredModule1/2.5/NestedRequiredModule1.psd1

@@ -8,13 +8,13 @@ ModuleVersion = '2.5'
 GUID = '369f0ee4-4cda-4ac3-a5c5-08e7bbc06e1a'
 
 # Author of this module
-Author = 'manikb'
+Author = 'PowerShell'
 
 # Company or vendor of this module
-CompanyName = 'Unknown'
+CompanyName = 'Microsoft Corporation'
 
 # Copyright statement for this module
-Copyright = '(c) 2015 manikb. All rights reserved.'
+Copyright = 'Copyright (c) Microsoft Corporation. All rights reserved.'
 
 # Description of the functionality provided by this module
 Description = 'NestedRequiredModule1 module'

test/powershell/engine/Module/assets/testmodulerunspace/NestedRequiredModule1/2.5/NestedRequiredModule1.psm1

@@ -1 +1,3 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
 function Get-NestedRequiredModule1 { Get-Date }