refactor(steam): merge all steam code into shared launcher

[wizzomafizzo]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 72.48062% with 71 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/platforms/shared/steam/scanner.go	61.11%	30 Missing and 12 partials ⚠️
pkg/platforms/shared/steam/launchers.go	51.85%	12 Missing and 1 partial ⚠️
pkg/platforms/linux/installer/install.go	33.33%	8 Missing ⚠️
pkg/config/configlaunchers.go	0.00%	4 Missing ⚠️
pkg/platforms/shared/steam/client_linux.go	91.66%	3 Missing and 1 partial ⚠️

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