improve generic_mapper to send event when finished loading (Mudlet#7556)

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#### Brief overview of PR changes/additions
Add event to generic_mapper. Send event `mapperScriptLoaded` with
argument `generic_mapper` when finished loading ie.
`raiseEvent("mapperScriptLoaded", "generic_mapper")`

#### Motivation for adding to Mudlet
Better scripter experience.

#### Other info (issues closed, discussion etc)
Also updated and moved the (currently unused) generic_mapper.mpackage to
the Lua package subdirectory.
closes Mudlet#7533

src/mudlet-lua/lua/generic-mapper/generic_mapper.xml

@@ -4159,6 +4159,7 @@ function map.eventHandler(event, ...)
         end
     elseif event == "sysLoadEvent" or event == "sysInstall" then
         config()
+        raiseEvent("mapperScriptLoaded", "generic_mapper")
     elseif event == "mapOpenEvent" then
         if not help_shown and not map.save.prompt_pattern[map.character or ""] then
             map.find_prompt()

src/mudlet-lua/lua/generic-mapper/versions.lua

@@ -5,5 +5,5 @@ return {{[1] = [[2.0]],[2] = [[2.0.1]],[3] = [[2.0.2]],[4] = [[2.0.3]],[5] = [[2
     [13] = [[2.0.12]], [14] = [[2.0.13]], [15] = [[2.0.14]], [16] = [[2.0.15]], [17] = [[2.0.16]], [18] = [[2.0.17]],
     [19] = [[2.0.18]], [20] = [[2.0.19]], [21] = [[2.0.20]], [22] = [[2.0.21]], [23] = [[2.0.22]], [24] = [[2.0.23]],
     [25] = [[2.0.24]], [26] = [[2.0.25]], [27] = [[2.0.26]], [28] = [[2.0.27]], [29] = [[2.1.0]], [30] = [[2.1.1]],
-    [31] = [[2.1.2]], [32] = [[2.1.3]]
+    [31] = [[2.1.2]], [32] = [[2.1.3]], [33] = [[2.1.4]]
 }}