Create MultiNode Adaptor

[DylanTinianov]

Description

Ticket: https://smartcontract-it.atlassian.net/browse/BCFR-1071

Most of the code in the Solana MultiNodeClient can be reused by all chain integrations. This PR extracts all of the chain-agnostic client code through making a generic MultiNodeClient. This will further extract functionality into the MultiNode and reduce new integration cost.

Generic MultiNodeAdaptor:

type MultiNodeAdaptor[RPC any, HEAD Head] struct {
	cfg         *mnCfg.MultiNodeConfig
	rpc         *RPC
	stateMu     sync.RWMutex // protects state* fields
	subsSliceMu sync.RWMutex
	subs        map[Subscription]struct{}
    chStopInFlight chan struct{}
	chainInfoLock sync.RWMutex
	highestUserObservations ChainInfo
	latestChainInfo ChainInfo
	
	// chain-specific functions will be passed in
	latestBlock          func(ctx context.Context, rpc *RPC) (HEAD, error)
	latestFinalizedBlock func(ctx context.Context, rpc *RPC) (HEAD, error)
}

The the following methods can all be chain-agnostic and extracted:

RegisterSub(sub Subscription, stopInFLightCh chan struct{}) 
LatestBlock(ctx context.Context) (HEAD, error) 
LatestFinalizedBlock(ctx context.Context) (HEAD, error) 
SubscribeToHeads
SubscribeToFinalizedHeads
OnNewHead
OnNewFinalizedHead
MakeQueryCtx
AcquireQueryCtx
UnsubscribeAllExcept
CancelInflightRequests
Close
GetInterceptedChainInfo

All other client methods will still be implemented on the chain specific side including:

Dial(ctx context.Context) error 
IsSyncing()
Ping(ctx context.Context) 
SendTxResult