feat(steamvr): auto-unblock ALVR driver on startup

[skryvel]

I'm really not sure what the path is on Windows. I found some references but not a full path, and especially it varies.

This will go into steamvr.vrsettings and toggle blocked_by_safe_mode if needed for the ALVR driver. Should fail gracefully as long as the file exists.

Windows is not implemented because:

• on Discord the point was raised that Windows SteamVR gets/causes much less trouble with this;
• the path gets more complicated and no source of truth on the web was found that felt safe to quickly implement.

[zmerp]

To avoid crashes, all unwrap()s should be removed and replaced with proper error handling

[skryvel]

To avoid crashes, all unwrap()s should be removed and replaced with proper error handling

Fixed. Feel free to point me to any other samples or let me know of any nits -- I'm relatively new to Rust in such a code-base.

[zmerp]

Overall this looks good to me. Someone else on linux like @Meister1593 should also review and test this PR before merging.

[Meister1593]

Simulated scenario (put crash state into same file), works fine, though i rarely get any real crash events nowadays.
Only small changes needed, otherwise looks good

[The-personified-devil]

Haven't tested it (and I honestly can't be bothered to force steamvr to crash), but lgtm (tho quite verbose, which might honestly be good considering this is messing with steamvr's rather fragile internals).

[gabriele2000]

Simulated scenario (put crash state into same file), works fine, though i rarely get any real crash events nowadays. Only small changes needed, otherwise looks good

Rarely?
SteamVR is as fragile as touching 20 year-old code, it crashes a lot, it's riddled with issues... consider yourself lucky