fix: use sync.Map in request transpot's packet conn server

[xiaokangwang]

This pull request fixes the issue within packet conn server, where a map is accessed without protection.

Thanks @dyhkwong for reporting this bug.

fatal error: concurrent map read and map write

goroutine 4895 [running]:
github.com/v2fly/v2ray-core/v5/transport/internet/request/assembler/packetconn.(*requestToPacketConnServer).OnRoundTrip(0xc000639e30, {0x1d514e8, 0xc000639cb0}, {{0xc00b3a8800, 0x0, 0x200}, {0xc006268940, 0x10, 0x10}}, {0xc0000907a0, ...})
	github.com/v2fly/v2ray-core/v5/transport/internet/request/assembler/packetconn/req2packet.go:206 +0xd3
github.com/v2fly/v2ray-core/v5/transport/internet/request/assembler/packetconn.(*udpAssemblerServer).OnRoundTrip(0xc00c8bfa28?, {0x1d514e8?, 0xc000639cb0?}, {{0xc00b3a8800, 0x0, 0x200}, {0xc006268940, 0x10, 0x10}}, {0xc0000907a0, ...})
	github.com/v2fly/v2ray-core/v5/transport/internet/request/assembler/packetconn/udpassemblerServer.go:144 +0x8b
github.com/v2fly/v2ray-core/v5/transport/internet/request/roundtripper/httprt.(*httpTripperServer).onRequest(0xc00062cfc0, {0x1d4cbf0, 0xc007710e00}, 0xc00736d560)
	github.com/v2fly/v2ray-core/v5/transport/internet/request/roundtripper/httprt/httprt.go:151 +0x4a4
github.com/v2fly/v2ray-core/v5/transport/internet/request/roundtripper/httprt.(*httpTripperServer).ServeHTTP(0x9e12f9?, {0x1d4cbf0?, 0xc007710e00?}, 0xc00c8bfb68?)
	github.com/v2fly/v2ray-core/v5/transport/internet/request/roundtripper/httprt/httprt.go:111 +0x1d
net/http.serverHandler.ServeHTTP({0xc0075517d0?}, {0x1d4cbf0?, 0xc007710e00?}, 0x6?)
	net/http/server.go:3142 +0x8e
net/http.(*conn).serve(0xc007e7c120, {0x1d514e8, 0xc00068a0f0})
	net/http/server.go:2044 +0x5e8
created by net/http.(*Server).Serve in goroutine 7
	net/http/server.go:3290 +0x4b4

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.

Project coverage is 35.00%. Comparing base (346ca66) to head (8ba512c).
Report is 31 commits behind head on master.

Files	Patch %	Lines
...nternet/request/assembler/packetconn/req2packet.go	0.00%	13 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3130      +/-   ##
==========================================
- Coverage   35.59%   35.00%   -0.60%     
==========================================
  Files         729      741      +12     
  Lines       41613    42596     +983     
==========================================
+ Hits        14812    14910      +98     
- Misses      25167    26046     +879     
- Partials     1634     1640       +6     

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