Replaces fs-err for some snapshot errors

[brooksprumo]

Problem

The fs-err create does not include source errors when displaying the error. The solana repo's convention is to include the source error in the message, so we end up losing the underlying cause of an IO error if fs_err is used.

Here's more info about the issue that I raised on the fs-err repo: andrewhickman/fs-err#51. Turns out their behavior is desired, and likely the most idiomatically correct Rust way. But we're not going to change the solana repo's error reporting anytime soon. Instead, we should replace the use of fs-err with regular std::fs.

Related: #34799

Summary of Changes

Replace fs-err for all the AddBankSnapshotError and GetSnapshotAccountsHardLinkDirError errors

[codecov]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (8f9d915) 81.8% compared to head (09c488e) 81.7%.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #34837     +/-   ##
=========================================
- Coverage    81.8%    81.7%   -0.1%     
=========================================
  Files         825      825             
  Lines      223269   223276      +7     
=========================================
- Hits       182635   182611     -24     
- Misses      40634    40665     +31     

[apfitzge]

lgtm!