Move remaining functions out rct2.c

Implement #2225: Change mountain tool to ignore higher surrounding tiles

- rct2_init_directories
- get_file_path

Regression from #5775.

No palette was loaded, so load it in game_init_all.

Fixes #2225. The mountain tool will now stop at land edges. It also improves the performance of the mountain tool.

Saves a few lines of code

Errors in game_command_raise/lower_land will now be passed on in
smooth_land. Removes need for error checking elsewhere

Behaviour now matches that of the non-mountain land tool. Provide define
for min/max land height and fix a bug where the mountain tool would
incorrect raise/lower land.

Change the landscaping cost to be $5 per quarter cell changed. This
normalizes the cost for the maintain tool.

This makes the mountain tool calculate the cost properly. Fixes #2229,

Fix #6052: Unable to place entrance/exit on certain ride types.

The issue is caused by ride types that don't automatically close the construction window which leads to execute following condition:
https://github.com/OpenRCT2/OpenRCT2/blob/develop/src/openrct2/world/map.c#L3374-L3378
Which later executes GAME_COMMAND_REMOVE_TRACK with the ghost flag set:
https://github.com/OpenRCT2/OpenRCT2/blob/develop/src/openrct2/ride/ride.c#L1416-L1424
But then ignores the ghost flag and removes the entrances. I've also refactored the flags to use the actual named flags.

Show up to 128 open rides in the New Campaign dropdown.