Add foundationdb-simulation crate

[Wonshtrum]

This crate aims to provide a framework to easily test in the Foundationdb simulator Rust layers built with foundation-rs.
To do so, Rust workloads that implement the RustWorkload trait, are "registered" using the simulation_entrypoint macro and compiled as a "cdylib", will be recognized as ExternalWorkload by the fdbsever. More info in foundationdb-simulation/docs/README.md.

[coveralls]

Pull Request Test Coverage Report for Build 5997250982

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 115 unchanged lines in 8 files lost coverage.
• Overall coverage increased (+1.0%) to 73.679%

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Files with Coverage Reduction	New Missed Lines	%
foundationdb/src/directory/mod.rs	2	92.56%
foundationdb/src/transaction.rs	3	86.87%
foundationdb/src/directory/directory_layer.rs	7	93.22%
foundationdb/src/directory/directory_partition.rs	9	75.0%
foundationdb-bindingtester/src/main.rs	11	88.05%
foundationdb/src/database.rs	11	60.43%
foundationdb/src/tuple/pack.rs	35	86.21%
foundationdb/src/tenant.rs	37	0.0%

Totals
Change from base Build 5940346972:	1.0%
Covered Lines:	4126
Relevant Lines:	5600

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💛 - Coveralls

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +2.62% 🎉

Comparison is base (23f4b58) 79.89% compared to head (a12f7ea) 82.51%.

❗ Current head a12f7ea differs from pull request most recent head 5cb0f42. Consider uploading reports for the commit 5cb0f42 to get more accurate results

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #101      +/-   ##
==========================================
+ Coverage   79.89%   82.51%   +2.62%     
==========================================
  Files          27       23       -4     
  Lines        5212     4844     -368     
==========================================
- Hits         4164     3997     -167     
+ Misses       1048      847     -201     

see 13 files with indirect coverage changes

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