Update CacheSizeTracker and LogSizeTracker

[TedHartMS]

Major features:

• Support fine-grained HeadAddress movement (not at page boundary). E.g. if we have a page with a large number of large objects, we can "evict" by clearing individual records, reclaiming the space without having to evict the entire page.
• Combine the "inline log space" size limit with the heap size limit into one number, and meet this limit by a combination of page and object eviction.
• SizeTracker is automatically enabled if "memorySize" is specified; this is a limit. If only pageSize and pageCount are specified, there will be no size tracking. PageSize must be specified. If only memorySize and pageSize are specified, the pageCount is calculated from those. PageCount becomes MaxAllocatedPageCount which cannot be changed (although the actual number of allocated pages may be smaller to satisfy the limit). If all 3 are specified, then pageCount is assumed to be intended to limit MaxAllocatedPageCount to be less than (memorySize / pageSize).
• The "EmptyPageCount" property is removed, although we still have empty pages. This is replaced by MaxAllocatedPageCount which is set from the initial LogSettings and does not change (although eviction may reduce the actual number of allocated pages, it will not exceed this).

There are a number of temporarily [Explicit] tests that still require work to modify from the previous implementation; that work is in progress.

[Copilot]

Pull request overview

This PR implements major changes to CacheSizeTracker and LogSizeTracker to enable fine-grained HeadAddress movement (not constrained to page boundaries), combining inline log space and heap size limits into a unified memory target. The implementation automatically enables size tracking when memorySize is specified, and introduces the ability to specify pageCount independently. The PR also removes the EmptyPageCount property in favor of MaxAllocatedPageCount.

Changes:

• Renamed configuration properties from MemorySize/HeapMemorySize to LogMemorySize with combined inline+heap tracking
• Added PageCount configuration option to allow specifying page count independent of memory size
• Replaced EmptyPageCount with MaxAllocatedPageCount (now HighWaterAllocatedPageCount)
• Implemented fine-grained eviction that can clear individual records within pages
• Updated size tracking to use observer pattern and track both inline and heap memory together

Reviewed changes

Copilot reviewed 129 out of 130 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
ServerOptions.cs	Renamed MemorySize to LogMemorySize, added PageCount, renamed IndexSize to IndexMemorySize
GarnetServerOptions.cs	Removed HeapMemorySize/ReadCacheHeapMemorySize, added ReadCachePageCount, updated logging
KVSettings.cs	Changed MemorySize to LogMemorySize, added PageCount, removed MinEmptyPageCount
LogSettings.cs	Updated to use MemorySize (long) instead of MemorySizeBits, added PageCount
CacheSizeTracker.cs	Removed LogSizeCalculator, updated to track combined inline+heap memory
TestUtils.cs	Updated test utilities to use new configuration names and pageCount parameter
Various test files	Updated memory size parameters and adjusted for new MinTargetPageCount requirements
Allocator implementations	Updated FreePage logic to check logSizeTracker instead of EmptyPageCount

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