Binance,Okx: Add Leverage, MarginType, Positions and CollateralMode support (#1220)

* init

* surprise train commit

* basic distinctions

* the terms of binance are confusing

* renames and introduction of allocatedMargin

* add new margin funcs

* pulling out wires

* implement proper getposition stuff

* bad coding day

* investigate order manager next

* a broken mess, but a progressing one

* finally completes some usdtmargined stuff

* coinMfutures eludes me

* expand to okx

* imports fix

* completes okx wrapper implementations

* cleans and polishes before rpc implementations

* rpc setup, order manager features, exch features

* more rpc, collateral and margin things

* mini test

* looking at rpc response, expansion of features

* reorganising before the storm

* changing how futures requests work

* cleanup and tests of cli usage

* remove silly client side logic

* cleanup

* collateral package, typo fix, margin err, rpc derive

* uses convert.StringToFloat ONLY ON STRUCTS FROM THIS PR

* fix binance order history bug

* niteroos

* adds new funcs to exchange standards testing

* more post merge fixes

* fix binance

* replace simepletimeformat

* fix for merge

* merge fixes

* micro fixes

* order side now required for leverage

* fix up the rest

* global -> portfolio collateral

* Update exchanges/collateral/collateral_test.go

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* adds fields and todos

* rm field redundancy

* lint fix oopsie daisy

* fixes panic, expands error and cli explanations (sorry shaz)

* ensures casing is appropriate for underlying

* Adds a shiny TODO

---------

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

exchanges/margin/margin.go

@@ -0,0 +1,67 @@
+package margin
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// Valid returns whether the margin type is valid
+func (t Type) Valid() bool {
+	return t != Unset && supported&t == t
+}
+
+// UnmarshalJSON converts json into margin type
+func (t *Type) UnmarshalJSON(d []byte) error {
+	var marginType string
+	err := json.Unmarshal(d, &marginType)
+	if err != nil {
+		return err
+	}
+	*t, err = StringToMarginType(marginType)
+	return err
+}
+
+// String returns the string representation of the margin type in lowercase
+// the absence of a lower func should hopefully highlight that String is lower
+func (t Type) String() string {
+	switch t {
+	case Unset:
+		return unsetStr
+	case Isolated:
+		return isolatedStr
+	case Multi:
+		return multiStr
+	case Unknown:
+		return unknownStr
+	}
+	return ""
+}
+
+// Upper returns the upper case string representation of the margin type
+func (t Type) Upper() string {
+	return strings.ToUpper(t.String())
+}
+
+// IsValidString checks to see if the supplied string is a valid margin type
+func IsValidString(m string) bool {
+	switch strings.ToLower(m) {
+	case isolatedStr, multiStr, unsetStr, crossedStr, crossStr:
+		return true
+	}
+	return false
+}
+
+// StringToMarginType converts a string to a margin type
+// doesn't error, just returns unknown if the string is not recognised
+func StringToMarginType(m string) (Type, error) {
+	switch strings.ToLower(m) {
+	case isolatedStr:
+		return Isolated, nil
+	case multiStr, crossedStr, crossStr:
+		return Multi, nil
+	case "":
+		return Unset, nil
+	}
+	return Unknown, fmt.Errorf("%w %v", ErrInvalidMarginType, m)
+}