Fix encoding/decoding of multi-byte first OID subidentifier

[spokodev]

Problem

asn1.oidToDer / asn1.derToOid mis-handle the first OID subidentifier when it spans more than one byte. The first subidentifier encodes the first two arcs as 40 * arc1 + arc2; per X.690 §8.19 it is a base-128 multi-byte value like every other subidentifier, so for arc1 === 2 (where arc2 is unbounded) it routinely exceeds one byte. Both directions corrupt such OIDs:

const forge = require('node-forge');
forge.asn1.oidToDer('2.999.3').toHex();                  // '43703'     wrong (X.690: '883703')
forge.asn1.derToOid(forge.util.hexToBytes('883703'));   // '3.16.55.3' wrong (X.690: '2.999.3')
forge.asn1.oidToDer('2.100').toHex();                   // 'b4'        wrong (X.690: '8134')

• Encode writes 40*arc1 + arc2 with a single putByte, truncating values ≥ 256 and never setting the continuation bit (so values in 128–255 produce a byte a decoder reads as "more bytes follow").
• Decode reads exactly one byte and splits it, ignoring the continuation bit, so a multi-byte first subidentifier is shredded into bogus arcs (and can emit a structurally impossible root arc of 3).

This is not limited to the 2.999 example arc: registered arcs that appear in real certificates are affected, e.g. 2.41.x (biometrics, ISO/IEC JTC 1 SC 37), 2.49.x (NATO), 2.51.x (GS1). Any DER carrying such an OID is written wrong and read wrong.

Fix

• oidToDer: feed the first subidentifier through the existing base-128 emitter instead of a raw putByte.
• derToOid: accumulate the first subidentifier across continuation bytes like every other subidentifier, then split it (value < 80 → ⌊value/40⌋.value%40, else 2.(value−80)).

Verification

• New round-trip tests for a multi-byte first subidentifier (2.999.3 ↔ 883703, 2.100 ↔ 8134); they fail on main and pass with the fix.
• Output cross-checked against OpenSSL asn1parse and an independent X.690 §8.19 implementation across an OID fuzz (first-arc sweeps + random wide arcs): 0 mismatches, and 0 changes to previously-correct OIDs.
• The existing asn1, oids, x509, pem suites pass unchanged.

The pre-existing >32-bit-arc limitation (the 0xffffffff guard / TODO) is unchanged and out of scope.