Don't count support gems when deciding if a gem group is provided

[lucaskarsten]

Related to #2400.

Description of the problem being solved:

SkillsTabClass:UpdateGlobalGemCountAssignments decides whether a socket group counts against the skill slot limit, but it re-evaluates provided for every enabled gem in the group:

for _, gemInstance in ipairs(socketGroup.gemList) do
    if gemInstance.enabled and not countGroup then
        local grantedEffect = gemInstance.grantedEffect or gemInstance.gemData and gemInstance.gemData.grantedEffect
        local provided = gemInstance.fromItem or gemInstance.fromTree or
            grantedEffect and (grantedEffect.fromItem or grantedEffect.fromTree)
        countGroup = not provided
    end

The guard only stops re-evaluation once countGroup is already true, so while it is false every further gem gets to overwrite the decision. Support gems carry neither fromItem nor fromTree, which means a single support is enough to flip a provided group to counted.

Two cases hit this:

• The default weapon attacks. MeleeBowPlayer and friends carry fromItem = true in Data/Skills/other.lua, so Bow Shot on its own is correctly exempt. Socketing any support into it makes the group count, and a character with 9 real skills reports 10.
• Skills granted by an equipped item, where fromItem is set on the gem instance in CalcSetup.lua (activeGemInstance.fromItem = grantedSkill.sourceItem ~= nil). Same result once a support is added.

Support gems never occupy a skill slot on their own, so they are now skipped when determining whether the group is provided. Active skills still decide, and a group holding several active skills still counts once.

Steps taken to verify a working solution:

• Added spec/System/TestGemGroupCount_spec.lua covering both granted paths plus the normal, supported-normal and disabled-group cases. Against dev it reports 4 successes / 2 failures; with the fix, 6 successes / 0 failures.
• Ran the full busted suite in ghcr.io/pathofbuildingcommunity/pathofbuilding-tests:latest: 571 successes / 0 failures / 0 errors.
• Reproduced by hand on a level 76 Deadeye with 9 allocated skills. Bow Shot alone raises no warning; adding Rapid Attacks I to it produces "You have too many gem groups allocated. Max allowed is 9. You have 10 non-item/non-granted gem groups allocated." The warning is gone with the fix.

Link to a build that showcases this PR:

Any bow build with 9 allocated skills that also keeps a supported Bow Shot group. The spec reproduces it without a build file.

Before screenshot:

4 successes / 2 failures in the new spec, and the skill slot warning shown above.

After screenshot:

6 successes / 0 failures in the new spec, 571 successes / 0 failures for the whole suite, and no warning.