Add Helptext for resources in packaged rulesets

[jwrober]

Is your feature request related to a problem? Please describe. We don't provide extra helptext in default packaged ruleset for tile special resources. This leaves help incomplete.

Describe the solution you'd like Fill in the helptext field for the tile resources in terrain.ruleset for the following rulesets we package:

• default/civ2civ3
• classic
• civ1
• civ2
• experimental

Describe alternatives you've considered None

Additional context Attempting to make the in game help more immersive with fully populated information on the ruleset being played

[lmoureaux]

https://github.com/longturn/freeciv21/blob/eff5fd14f815080f333ac763a470c9ac8ee2781f/common/networking/packets.def#L2064-L2068

[lmoureaux]

Steps:

1. Add the information to one resource in your favorite ruleset. Make sure to use a _("translatable string")
2. Add support for loading it in load_terrain_names (ruleset.cpp)
3. Add a new network capability and a new field to PACKET_RULESET_RESOURCE controlled by this capability
4. Update send_ruleset_extras, send_ruleset_bases, send_ruleset_roads and the receiving functions to use this information (providing a fallback when it doesn't exist)
5. Update helpdata.cpp to display the help text

[lmoureaux]

Here is an example commit that changes the network protocol: https://github.com/longturn/freeciv21/commit/76f85245fa16a899d285cc12dcddffcb209cca80