Make the names of graph structs consistent

[universato]

main

Now: SccGraph, MfGraph, MinCostFlowGraph

• The name style of the struct is different.

Expected1: Scc(or SCC), MaxFlow, MinCostFlow

• Short and readable.
• Each struct name equals each file name.

Expected2: SccGraph, MaxFlowGraph, MinCostFlowGraph

• Long but readable.
• No other language library has adopted this idea.

Expected3: SccGraph, MfGraph, McfGraph

• Too short, not readable (except for SccGraph).
• These names are closest to the original C++ library.

All graph names need to be changed, but I prefer expected1.

Other data structures

In reference,

lang	struct, impl	file
Rust	Dsu	dsu	URL
Rust	SccGraph	scc	URL
Rust	MfGraph	maxflow	URL
Rust	MinCostFlowGraph	mincostflow	URL
Rust	Segtree	segtree	URL
Rust	LazySegtree	lazysegtree	URL
Rust	TwoSat	twosat	URL
Rust	ModInt	modint	URL

Other language libraries

In reference,

Lang	SCC	MaxFlow	MinCostFlow
C++	scc_graph	mf_graph	mcf_graph
C#	SccGraph	MFGraph/MaxFlow.cs	McfGraph/MinCostFlow.cs
Python	SCCGprah	MFGraph	MCFGraph
Rust	SccGraph	MfGraph	MinCostFlowGraph
Go	SccGraph	---	---
D	SccGraph	MfGraph	McfGraph
Java	SCC	MaxFlow	MinCostFlow
Kotolin	SCC	MaxFlow	MinCostFlow
Ruby	SCC	MaxFlow	MinCostFlow
Crystal	SCC	MaxFlow	MinCostFlow

[TonalidadeHidrica]

This is just renaming the names, so it may be worth considering before the language update.

[qryxip]

@TonalidadeHidrica @mizar I prefer "Expected2". What do you think?