Core Tools build and release pipeline fixes/improvements

[Francisco-Gamino]

Fix MSI and signing the Core Tools build

Release pipeline https://azfunc.visualstudio.com/Azure%20Functions/_releaseDefinition?definitionId=23&_a=definition-tasks&environmentId=113

1. Update Upload to storage task to check with an exe to make sure that the binaries are signed

• verify the minfied zip files
• verify the msi are present and signed
• verify the nuget package (Microsoft.Azure.Functions.CoreTools..nupkg) is present and signed

2. Update the Core Tools pipeline -- make signing and MSI generation contingent on branch names that are defined as list in build variables populate with common ones (ex. release_3.0, etc) but folks will be able to add as needed for specific builds

[Francisco-Gamino]

cc @soninaren @kashimiz @michaelpeng36 @AnatoliB

[apawast]

Closing this issue as all points should be addressed.