Add glove_skin custom property for extracting glove skin names

[jtoelli]

## Summary
Adds glove_skin as a new custom property to parse_ticks(), enabling extraction of glove skin names directly from demo files.

## Motivation
Currently, glove data fields (glove_paint_id, glove_paint_seed, glove_paint_float) are available, but there's no way to get the actual glove skin name (e.g., "Imperial Plaid", "Polygon"). This PR adds glove_skin to match the existing weapon_skin functionality.

## Changes

• prop_controller.rs: Added GLOVE_SKIN constant (ID: 20000003)
• maps.rs: Registered glove_skin in:
  • CUSTOM_PLAYER_PROP_IDS map
  • FRIENDLY_NAMES_MAPPING map
  • PropType enum mapping
• collect_data.rs: Added find_glove_skin() function that performs PAINTKITS lookup
• collect_data.rs: Added error variants for glove skin operations

## Usage Example

from demoparser2 import DemoParser

parser = DemoParser("demo.dem")
df = parser.parse_ticks(['glove_skin', 'glove_paint_id', 'glove_paint_seed'])

# Returns DataFrame with glove_skin column containing names like:
# "Imperial Plaid", "Polygon", "Amphibious", "Racing Green", etc.

## Testing
Tested on a cs2 replay and it worked for me :)

## Implementation Note
The glove_skin field performs a PAINTKITS lookup based on glove_paint_id. Users should check glove_item_idx > 0 in their code to distinguish between players actively wearing custom gloves versus those with default gloves (as players may have a paint_id in inventory without wearing custom gloves).

[LaihoE]

Thanks