lang: generic structs not parsed correctly into IDL

[charlieyou]

Example:

#[account]
pub struct Example {
    pub value: SlotTrackedValue<u64>,
}
#[derive(AnchorDeserialize, AnchorSerialize, Clone, Copy, Debug, Default)]
pub struct SlotTrackedValue<T> {
    pub value: T,
    pub last_update: LastUpdate,
}

gets parsed into the IDL as:

...
 {
    name: "value",
    type: {
        defined: "SlotTrackedValue<u64>",
    },
},
...
types: [
  {
    name: "SlotTrackedValue",
    type: {
        kind: "struct",
        fields: [
            {
                name: "value",
                type: {
                    defined: "T",
                },
            },
            {
                name: "lastUpdate",
                type: {
                    defined: "LastUpdate",
                },
            },
        ],
    },
  },
]

[acheroncrypto]

Fixed by #2824.