Fail the RPM build if FPM tool is not present

[NikolaMilosavljevic]

Currently, if the build is supposed to produce RPM packages, but the tooling (i.e. fpm) is missing, a message will be logged and the build will skip the RPM package generation. This can result in successful builds that are missing the required artifacts.

Additional changes were needed, as RPM targets were being executed for any build that was running on RPM-based distro due to:

sdk/src/Installer/redist-installer/targets/GenerateRPMs.targets

Lines 14 to 16 in c1ff1eb

	<Target Name="GenerateRpmsInner"
	DependsOnTargets="TestFPMTool;BuildRpms"
	Condition=" '$(IsRPMBasedDistro)' == 'True' "

The use of property IsRPMBasedDistro was overloaded to mean both that the distro is RPM-based and that we want to build installers.

Property was set here:

sdk/src/Installer/redist-installer/targets/GetRuntimeInformation.targets

Lines 29 to 30 in c1ff1eb

	<IsRPMBasedDistro Condition=" $(HostRid.StartsWith('rhel')) AND '$(HostRid)' != 'rhel.6-x64' ">true</IsRPMBasedDistro>
	<IsRPMBasedDistro Condition=" $(HostRid.StartsWith('centos')) ">true</IsRPMBasedDistro>

For installer build we were passing this same property, which was already being set on rpm-based distros, so this wasn't correct:

sdk/.vsts-ci.yml

Line 216 in c1ff1eb

osProperties: $(linuxOsPortableProperties) /p:IsRPMBasedDistro=true

I am now setting a different property, BuildSdkRpm, in scenarios where RPM packaging is desired. This matches DEB build experience, where we have a similar pair of properties: BuildSdkDeb and IsDebianBaseDistro.

Notes

Fix for 9.0.1xx - will be backported to other 9.0.x branches in support. Fix for 8.0 - dotnet/installer#20633

Contributes to dotnet/installer#20561

[NikolaMilosavljevic]

Regular (non-pkg) Linux leg is trying to build RPM packages - that shouldn't happen. More changes are needed.

[NikolaMilosavljevic]

I've applied the same changes from 8.0 PR, which is now passing all checks: dotnet/installer#20633

[NikolaMilosavljevic]

@marcpopMSFT can we merge this one? I think the branch is still open.