【Allocator】Add allocator visitor

[liuruyan]

PR Category

Performance Optimization

PR Types

New features

Description

本PR升级Allocator基础设施，新增Allocator Visitor，解决旧装饰器模式下，非顶层Allocator功能难以拓展及暴露的问题（想要暴露一个方法，只能再虚基类中加上方法，并在链路上所有Allocator中进行实现），具体改动如下：

1. 新增Allocator Visitor，在虚基类中接受Visitor对象，不同Visitor可以针对不同Allocator实现不同功能
2. 新增VmmMaxFreeSize方法，其使用Visitor实现返回VMM Allocator中空闲块状态（最大空闲块及前N大空闲块总和）

注：Visitor日后可根据需求进行升级（升级可变模板参数）
Pcard-67164

[paddle-bot]

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.93548% with 5 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@42b8146). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
paddle/phi/core/memory/allocation/allocator.h	0.00%	1 Missing ⚠️
...addle/phi/core/memory/allocation/retry_allocator.h	50.00%	1 Missing ⚠️
...ore/memory/allocation/stream_safe_cuda_allocator.h	75.00%	1 Missing ⚠️
paddle/phi/core/memory/mem_visitor.cc	95.65%	1 Missing ⚠️
paddle/phi/core/memory/mem_visitor.h	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop   #76349   +/-   ##
==========================================
  Coverage           ?   91.93%           
==========================================
  Files              ?       10           
  Lines              ?       62           
  Branches           ?        0           
==========================================
  Hits               ?       57           
  Misses             ?        5           
  Partials           ?        0           

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[wanghuancoder]

LGTM