Add support for FFMA without hugepages and using only mmap

[danielealbano]

This branch adds support for Fast Fixed Memory Allocator (FFMA) to function without hugepages and using only mmap.

Overall, it makes FFMA more versatile by allowing it to work without hugepages and with only mmap, which can improve its performance and efficiency in certain scenarios, but most importantly as FFMA doesn't suffer from memory fragmentation makes it a perfect choice for a long-running software like cachegrand as reduce the scope of any garbage collector that will be implemented down the line.

The only downside, currently, is that the storage_db has to operate using blocks of 64kb and this limits the maximum size of the chunks to about ~170MB of data.

This limitation will be removed with a future PR.

There are also some additional PRs planned to make FFMA less dependant on malloc and rely instead on mmap for its own internal allocations.

[codecov]

Codecov Report

Patch coverage: 87.86% and project coverage change: -0.02 ⚠️

Comparison is base (d0202e2) 81.71% compared to head (1584935) 81.70%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #296      +/-   ##
==========================================
- Coverage   81.71%   81.70%   -0.02%     
==========================================
  Files         161      163       +2     
  Lines       11009    11031      +22     
==========================================
+ Hits         8996     9012      +16     
- Misses       2013     2019       +6     

Flag	Coverage Δ
unittests	81.70% <87.86%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...rc/module/redis/command/module_redis_command_get.c	100.00% <ø> (ø)
...module/redis/command/module_redis_command_getdel.c	88.00% <ø> (ø)
.../module/redis/command/module_redis_command_getex.c	91.23% <ø> (ø)
...dule/redis/command/module_redis_command_getrange.c	93.10% <ø> (ø)
...module/redis/command/module_redis_command_getset.c	78.57% <ø> (ø)
...c/module/redis/command/module_redis_command_mget.c	81.25% <ø> (ø)
...module/redis/command/module_redis_command_rename.c	88.37% <ø> (ø)
...dule/redis/command/module_redis_command_renamenx.c	89.13% <ø> (ø)
...rc/module/redis/command/module_redis_command_set.c	88.61% <ø> (ø)
.../module/redis/command/module_redis_command_setex.c	89.47% <ø> (ø)
... and 9 more

... and 3 files with indirect coverage changes

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