Add single asset vault (XLS-65d) (#5224)

- Specification: XRPLF/XRPL-Standards#239
- Amendment: `SingleAssetVault`
- Implements a vault feature used to store a fungible asset (XRP, IOU, or MPT, but not NFT) and to receive shares in the vault (an MPT) in exchange.
- A vault can be private or public.
- A private vault can use permissioned domains, subject to the `PermissionedDomains` amendment.
- Shares can be exchanged back into asset with `VaultWithdraw`.
- Permissions on the asset in the vault are transitively applied on shares in the vault.
- Issuer of the asset in the vault can clawback with `VaultClawback`.
- Extended `MPTokenIssuance` with `DomainID`, used by the permissioned domain on the vault shares.

Co-authored-by: John Freeman <jfreeman08@gmail.com>

include/xrpl/protocol/STIssue.h

@@ -37,6 +37,7 @@ public:
     using value_type = Asset;
 
     STIssue() = default;
+    STIssue(STIssue const& rhs) = default;
 
     explicit STIssue(SerialIter& sit, SField const& name);
 
@@ -45,6 +46,9 @@ public:
 
     explicit STIssue(SField const& name);
 
+    STIssue&
+    operator=(STIssue const& rhs) = default;
+
     template <ValidIssueType TIss>
     TIss const&
     get() const;