refactor: pass large structure by const reference on every RPC call

[PastaPastaPasta]

Issue being fixed or feature implemented

We are passing this large data structure by value

I would argue that we backport this to 20.0.3 as this seems likely to cause significant performance hits on RPC calls; thoughts?

What was done?

Pass by const reference

How Has This Been Tested?

Building

Breaking Changes

None

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

[UdjinM6]

I wouldn't call this

dash/src/rpc/server.cpp

Lines 143 to 152 in 4fc4448

	mapPlatformRestrictions = {
	{"getbestblockhash", {}},
	{"getblockhash", {}},
	{"getblockcount", {}},
	{"getbestchainlock", {}},
	{"quorum", {"sign", static_cast<uint8_t>(Params().GetConsensus().llmqTypePlatform)}},
	{"quorum", {"verify"}},
	{"submitchainlock", {}},
	{"verifyislock", {}},
	};

large :) but makes sense to fix it anyway I guess.

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[ogabrielides]

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[knst]

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