fix(pkg): isolates dependency with github.com/odigos-io/go-rtml

[vroldanbet]

Description

This PR isolates dependency with github.com/odigos-io/go-rtml

The introduction of github.com/odigos-io/go-rtml as a dependency has caused many go toolchain operations to fail because it now requires special flags to resolve a runtime symbol. This is not ideal because it breaks the developer experience for folks using IDEs with native Go support. Something as simple as go test ./... no longer works without flags. But most importantly, it becomes sticky for any go module that imports SpiceDB.

This commit isolates the memory protection usage by:

• adding a global variable that acts as the registry
• isolating the MemoryUsageProvider into its own package
• introducing a new NoopMemoryLimiter, and using it everywhere we explicitly used the go-rtml package
• moving tests into isolated packages
• initializing the global default provider in main.go, using a function controlled by build tags. Without the memoryprotection build tag, it defaults to using the noop implementation.
• moving all tests in the main package to make sure one can run them without the need of passing the special flags.

Consequence:

• now all tests run without special flags, except for those where we explicitly test for this behavior.
• go modules importing SpiceDB do won't require the flags.
• Folks can run SpiceDB in their IDEs quickly without tinkering with toolchain flags

Testing

• Run main.go without tag should show a warning indicating it fell back to noop provider
• Run main.go with ldflags and memoryprotection tag, no warn log is printed, and log shows the type used
• run all mage commands that tounch something that uses ldflags and the tags
• build docker container and check logs, making sure the rtml limiter is in place

References

[codecov]

Codecov Report

❌ Patch coverage is 72.22222% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.05%. Comparing base (5baadbd) to head (97b8187).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...spicedb/memoryprotection/memory_protection_rtml.go	0.00%	2 Missing ⚠️
internal/middleware/memoryprotection/rtml/rtml.go	50.00%	2 Missing ⚠️
cmd/spicedb/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2734      +/-   ##
==========================================
+ Coverage   77.04%   77.05%   +0.01%     
==========================================
  Files         464      466       +2     
  Lines       49188    49199      +11     
==========================================
+ Hits        37891    37903      +12     
  Misses       8507     8507              
+ Partials     2790     2789       -1     

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[tstirrat15]

LGTM, but wondering about the function name.