Moving to use evgen keywords helper functions in transforms

The helpers seem like a nice way to do the same thing centrally instead of three times, and they avoid the warning currently in some evgen:

generate 03:17:20 2024-10-23 03:17:01,213 AthMpEvtLoopMgr...WARNING The file /cvmfs/atlas-nightlies.cern.ch/repo/sw/main_AthGeneration_x86_64-el9-gcc13-opt/2024-10-22T2126/AthGeneration/23.6.40/InstallArea/x86_64-el9-gcc13-opt/share/evgenkeywords.txt has not been registered with the FileMgr!

Apologies in case there's something I'm missing that makes this a bad idea; I hope @ewelina will say if I've misunderstood the aim of the helpers (note for the RC: please wait for a comment before merging, but I think L1 review can go ahead).

Generators/EvgenJobTransforms/share/skel.ABtoEVGEN.py

@@ -327,35 +327,8 @@ else:
 
 ## Check that the keywords are in the list of allowed words (and exit if processing an official JO)
 if evgenConfig.keywords:
-    ## Get the allowed keywords file from the JO package if possibe
-    # TODO: Make the package name configurable
-    kwfile = "EvgenJobTransforms/evgenkeywords.txt"
-    kwpath = None
-    for p in os.environ["JOBOPTSEARCHPATH"].split(":"):
-        kwpath = os.path.join(p, kwfile)
-        if os.path.exists(kwpath):
-            break
-        kwpath = None
-    ## Load the allowed keywords from the file
-    allowed_keywords = []
-    if kwpath:
-        evgenLog.info("evgenkeywords = " + kwpath)
-        kwf = open(kwpath, "r")
-        for l in kwf:
-            allowed_keywords += l.strip().lower().split()
-        ## Check the JO keywords against the allowed ones
-        evil_keywords = []
-        for k in evgenConfig.keywords:
-            if k not in allowed_keywords:
-                evil_keywords.append(k)
-        if evil_keywords:
-            msg = "evgenConfig.keywords contains non-standard keywords: %s. " % ", ".join(evil_keywords)
-            msg += "Please check the allowed keywords list and fix."
-            evgenLog.error(msg)
-            if officialJO:
-                sys.exit(1)
-    else:
-        evgenLog.warning("evgenkeywords = not found ")
+    from GeneratorConfig.GenConfigHelpers import checkKeywords
+    checkKeywords(evgenConfig, evgenLog, officialJO)
 
 ## Configure and schedule jet finding algorithms
 ## NOTE: This generates algorithms for jet containers defined in the user's JO fragment