Remake lastScheduledSync to save the 10 latest sync times instead the most recent one

[hsjoberg]

Currently writeLastScheduledSyncToDb() and writeLastScheduledSyncAttemptToDb() in LndMobileScheduledSyncWorker.java saves the most recent time.

blixt-wallet/android/app/src/main/java/com/blixtwallet/LndMobileScheduledSyncWorker.java

Lines 494 to 542 in f0678b7

	private void writeLastScheduledSyncAttemptToDb() {
	SQLiteDatabase db = dbSupplier.get();
	String key = "lastScheduledSyncAttempt";
	Long tsLong = System.currentTimeMillis() / 1000;
	String value = tsLong.toString();
	String sql = "INSERT OR REPLACE INTO catalystLocalStorage VALUES (?, ?);";
	SQLiteStatement statement = db.compileStatement(sql);
	try {
	db.beginTransaction();
	statement.clearBindings();
	statement.bindString(1, key);
	statement.bindString(2, value);
	statement.execute();
	db.setTransactionSuccessful();
	} catch (Exception e) {
	HyperLog.w(TAG, e.getMessage(), e);
	} finally {
	try {
	db.endTransaction();
	} catch (Exception e) {
	HyperLog.w(TAG, e.getMessage(), e);
	}
	}
	}
	private void writeLastScheduledSyncToDb() {
	SQLiteDatabase db = dbSupplier.get();
	String key = "lastScheduledSync";
	Long tsLong = System.currentTimeMillis() / 1000;
	String value = tsLong.toString();
	String sql = "INSERT OR REPLACE INTO catalystLocalStorage VALUES (?, ?);";
	SQLiteStatement statement = db.compileStatement(sql);
	try {
	db.beginTransaction();
	statement.clearBindings();
	statement.bindString(1, key);
	statement.bindString(2, value);
	statement.execute();
	db.setTransactionSuccessful();
	} catch (Exception e) {
	HyperLog.w(TAG, e.getMessage(), e);
	} finally {
	try {
	db.endTransaction();
	} catch (Exception e) {
	HyperLog.w(TAG, e.getMessage(), e);
	}
	}
	}

Instead make this to a JSON array containing timestamps of the 10 most recent sync times.