Add support for StockGrantActivity

[hygt]

Example XML with free IBKR shares from the referral program:

<StockGrantActivities>
<StockGrantActivity accountId="U12345678" acctAlias="" model="" currency="USD" fxRateToBase="0.86027"
assetCategory="STK" subCategory="COMMON" symbol="IBKR" description="INTERACTIVE BROKERS GRO-CL A"
conid="43645865" securityID="US45841N1072" securityIDType="ISIN" cusip="45841N107" isin="US45841N1072"
figi="BBG000LV0836" listingExchange="NASDAQ" underlyingConid="" underlyingSymbol="IBKR" underlyingSecurityID=""
underlyingListingExchange="" issuer="" issuerCountryCode="US" multiplier="1" strike="" expiry="" putCall="" 
principalAdjustFactor="" reportDate="20250407" activityDescription="Stock Award Grant for Cash Deposit" 
awardDate="20250407" vestingDate="20260407" quantity="0.7955" price="146.08" value="116.21" serialNumber="" 
deliveryType="" commodityType="" fineness="0.0" weight="0.0" />
<StockGrantActivity accountId="U12345678" acctAlias="" model="" currency="USD" fxRateToBase="0.80423" 
assetCategory="STK" subCategory="COMMON" symbol="IBKR" description="INTERACTIVE BROKERS GRO-CL A" 
conid="43645865" securityID="US45841N1072" securityIDType="ISIN" cusip="45841N107" isin="US45841N1072" 
figi="BBG000LV0836" listingExchange="NASDAQ" underlyingConid="" underlyingSymbol="IBKR" underlyingSecurityID="" 
underlyingListingExchange="" issuer="" issuerCountryCode="US" multiplier="1" strike="" expiry="" putCall="" 
principalAdjustFactor="" reportDate="20250903" activityDescription="Stock Award Grant for Cash Deposit" 
awardDate="20250903" vestingDate="20260903" quantity="3.8905" price="63.9" value="248.6" serialNumber="" 
deliveryType="" commodityType="" fineness="0.0" weight="0.0" />
<StockGrantActivity accountId="U12345678" acctAlias="" model="" currency="USD" fxRateToBase="0.79602" 
assetCategory="STK" subCategory="COMMON" symbol="IBKR" description="INTERACTIVE BROKERS GRO-CL A" 
conid="43645865" securityID="US45841N1072" securityIDType="ISIN" cusip="45841N107" isin="US45841N1072" 
figi="BBG000LV0836" listingExchange="NASDAQ" underlyingConid="" underlyingSymbol="IBKR" underlyingSecurityID="" 
underlyingListingExchange="" issuer="" issuerCountryCode="US" multiplier="1" strike="" expiry="" putCall="" 
principalAdjustFactor="" reportDate="20251212" activityDescription="Stock Award Grant for Cash Deposit" 
awardDate="20251212" vestingDate="20261211" quantity="1.5798" price="66.06" value="104.36" serialNumber="" 
deliveryType="" commodityType="" fineness="0.0" weight="0.0" />
</StockGrantActivities>