Database: Expand to full path for lmdb file location

[sedited]

The rust LMDB crate expects a full path for the location of the database directory.

This fixes an error where if the data_dir has a non-expanded (tilde) path, for example when running the farcaster node after a cargo install, LMDB will not be able to create a database.

Fixes #576

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 11.9%. Comparing base (57177d1) to head (cd86d82).
⚠️ Report is 1237 commits behind head on main.

Files with missing lines	Patch %	Lines
src/databased/opts.rs	0.0%	3 Missing ⚠️
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Additional details and impacted files

@@           Coverage Diff           @@
##            main    #585     +/-   ##
=======================================
- Coverage   11.9%   11.9%   -0.0%     
=======================================
  Files         34      34             
  Lines      10732   10735      +3     
=======================================
  Hits        1282    1282             
- Misses      9450    9453      +3     

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