Fix: convert string representation of sizes to numbers when generating SQL for expression

[yrudman]

Issue:
New Expression editor allows to select unit of measurement for some field (like MB, GB, etc...) and those units saved in expression. Example: {"<"=>{"field"=>"ManageIQ::Providers::InfraManager::Vm-allocated_disk_storage", "value"=>"2.gigabytes"}}
However, during SQL generation "2.gigabytes" was not converting to Integer:

[ActiveRecord::StatementInvalid]: PG::InvalidTextRepresentation:
ERROR:  invalid input syntax for type numeric: "2.gigabytes"
LINE 1: ...ares"."vm_or_template_id" = "vms"."id" LIMIT 1) < '2.gigabyt...
                                                             ^
: SELECT "vms".*, (SELECT  "hardwares"."memory_mb" FROM "hardwares"
WHERE "hardwares"."vm_or_template_id" = "vms"."id" LIMIT 1) AS mem_cpu FROM "vms"
WHERE "vms"."type" IN ('ManageIQ::Providers::InfraManager::Vm', 'VmXen', 
'ManageIQ::Providers::Kubevirt::InfraManager::Vm',
 'ManageIQ::Providers::Redhat::InfraManager::Vm',
'ManageIQ::Providers::Microsoft::InfraManager::Vm',
'ManageIQ::Providers::Vmware::InfraManager::Vm') AND "vms"."template" = $1
AND ((SELECT  (SELECT SUM("disks"."size") FROM "disks"
WHERE "hardwares"."id" = "disks"."hardware_id") FROM "hardwares"
WHERE "hardwares"."vm_or_template_id" = "vms"."id" LIMIT 1) < '2.gigabytes') 

FIX:
Convert human representation of sizes to Integer

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1696412

@miq-bot add-label bug, reporting, hammer/yes

[gtanzillo]

Small typo on method name. Should be convert_bytes_units

[yrudman]

@gtanzillo renamed to slightly more descriptive - convert_size_in_units_to_integer

[miq-bot]

Checked commits yrudman/manageiq@a84aac1~...a11845f with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
2 files checked, 0 offenses detected
Everything looks fine. 🍰

[simaishi]

Hammer backport details:

$ git log -1
commit 0046a864ffaa0284acd7c73fe338933ea1a1fd8e
Author: Gregg Tanzillo <gtanzill@redhat.com>
Date:   Thu Apr 18 13:52:14 2019 -0400

    Merge pull request #18649 from yrudman/convert-human-sizes-to-bytes-in-expression
    
    Fix: convert string representation of sizes to numbers when generating SQL for expression
    (cherry picked from commit db748333c85f0ed4c3100652976f92a5ef458f23)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1702077

[yrudman]

@miq-bot add-label changelog/yes