[♻️Housekeeping] Remove BufferPool class and use .net implementation

[pictos]

There're a lot of places where Litedb news up an array just to discard it later, this is bad for allocations and perf. So:

• I added the the ArrayPool provided by the .NET team
• Removed old Pool implementations and replace then by .NET's one
• Change, where is possible, in the code places that news up an array to discard then later to use the ArrayPool

[JKamsker]

Generally, i would love to see this step to finally happen.

• Why do we not centralize the buffer pool declaration or just use ArrayPool directly
• Is the additional dependency also required in newer versions? Will it be installed in net8? The ArrayPool in net8 is in System.Runtime

[mbdavid]

well done, thanks

resolved comments