add obj directory icon

[TruncatedDinoSour]

obj directory for object files, for example mycode.c => mycode.o

TODO

• Use cargo fmt
• Add necessary tests
• Update default config/theme in README (if applicable)
• Update man page at lsd/doc/lsd.md (if applicable)

[codecov-commenter]

Codecov Report

Merging #909 (442b715) into master (949128f) will not change coverage.
The diff coverage is n/a.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

@@           Coverage Diff           @@
##           master     #909   +/-   ##
=======================================
  Coverage   85.75%   85.75%           
=======================================
  Files          51       51           
  Lines        5005     5005           
=======================================
  Hits         4292     4292           
  Misses        713      713           

Files Changed	Coverage Δ
src/theme/icon.rs	100.00% <ø> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more