feat(foundationdb): Initial commit for tracing support

[PierreZ]

The goal of the PR is to enable some basic tracing capabilities to the foundationdb crate. It is behind a feature not enabled by default.

More tracing operations will be added, once the relevant issue will be fixed

[coveralls]

Pull Request Test Coverage Report for Build 3669655595

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 31 unchanged lines in 6 files lost coverage.
• Overall coverage increased (+0.3%) to 74.189%

---

Files with Coverage Reduction	New Missed Lines	%
foundationdb/src/directory/mod.rs	1	94.85%
foundationdb/src/transaction.rs	1	88.39%
foundationdb/src/directory/directory_subspace.rs	2	90.67%
foundationdb/src/directory/directory_layer.rs	8	92.32%
foundationdb/src/directory/directory_partition.rs	8	82.84%
foundationdb-bindingtester/src/main.rs	11	88.71%

Totals
Change from base Build 3669323292:	0.3%
Covered Lines:	4300
Relevant Lines:	5796

---

💛 - Coveralls

[codecov-commenter]

Codecov Report

Base: 82.44% // Head: 82.17% // Decreases project coverage by -0.27% ⚠️

Coverage data is based on head (77aeea6) compared to base (a77116e).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #81      +/-   ##
==========================================
- Coverage   82.44%   82.17%   -0.28%     
==========================================
  Files          26       26              
  Lines        5042     5044       +2     
==========================================
- Hits         4157     4145      -12     
- Misses        885      899      +14     

Impacted Files	Coverage Δ
foundationdb/src/database.rs	87.00% <ø> (ø)
foundationdb/src/transaction.rs	88.39% <100.00%> (+0.06%)	⬆️
foundationdb/src/directory/directory_layer.rs	92.32% <0.00%> (-2.03%)	⬇️
foundationdb/src/directory/directory_subspace.rs	90.66% <0.00%> (-1.34%)	⬇️
foundationdb-bindingtester/src/main.rs	88.71% <0.00%> (-1.03%)	⬇️
foundationdb/src/directory/mod.rs	94.85% <0.00%> (+1.47%)	⬆️
foundationdb/src/directory/directory_partition.rs	82.83% <0.00%> (+8.95%)	⬆️

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