Async + Multi Cache (#1741)

* fix: handle invalid signatureKeyPublic types in sender-key-state

- added extra check to ensure signatureKeyPublic is either a base64 string or a Buffer
- fallback to empty buffer when unexpected object type is received
- prevents ERR_INVALID_ARG_TYPE error in Buffer.from

* adjusted based on  @jlucaso1 recommmendation

* fix: handle chain key objects for skmsg group message decryption

previously, some sender chain keys were stored or retrieved as plain objects
(e.g. { '0': 85, '1': 100, ... }) instead of Buffers. this caused
"ERR_INVALID_ARG_TYPE" during initial decryption of skmsg group messages.

this fixes any chain key object is converted to a proper Buffer
before being passed to SenderChainKey.

* fix: add more robust checks and fallbacks

* feat: async cache

feat: async caching

* fix: linting issues

* fix: mget logic

---------

Co-authored-by: αѕтяσχ11 <devastro0010@gmail.com>

src/Signal/Group/sender-chain-key.ts

@@ -10,7 +10,6 @@ export class SenderChainKey {
 	constructor(iteration: number, chainKey: Uint8Array | Buffer) {
 		this.iteration = iteration
 		if (Buffer.isBuffer(chainKey)) {
-			// backported from @MartinSchere's PR
 			this.chainKey = chainKey
 		} else if (chainKey instanceof Uint8Array) {
 			this.chainKey = Buffer.from(chainKey)