feat/cosmetic: Move Proxy Contracts around (#498)

### Description

When we restructured the repo a while ago I moved the proxy contracts to
the legacy folder thinking that we might not deploy named proxies in the
future, and maybe upgrade to a more modern Proxy implementation, but we
have continued to add the proxies inside the `legacy` folder which
doesn't feel great as that folder is meant to be removed (and probably
can be at this point).

So in order to embrace what we're doing I propose collocating the proxy
contracts to the `contracts/tokens` directory. And as an addition to
that, I propose collocating all proxies with their contracts like Martin
also did in the `contracts/oracles` for the new ChainlinkRelayerFactory
contract and proxy. So I also moved around the proxies in
`contracts/proxies`.

This shouldn't really effect anything else.

### Other changes

- Renamed stabletokenPSO to stabletokenPHP

### Tested

Ran tests, all is well.

### Related issues

N/A

### Backwards compatibility

YES

### Documentation

N/A

---------

Co-authored-by: Bayological <[email protected]>
Co-authored-by: denviljclarke <[email protected]>

Author: 3 people

contracts/proxies/SortedOraclesProxy.sol renamed to contracts/common/SortedOraclesProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../common/Proxy.sol";
+import "./Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract SortedOraclesProxy is Proxy {

contracts/proxies/BiPoolManagerProxy.sol renamed to contracts/swap/BiPoolManagerProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract StableTokenBRLProxy is Proxy {

contracts/proxies/BrokerProxy.sol renamed to contracts/swap/BrokerProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract StableTokenCOPProxy is Proxy {

contracts/proxies/ReserveProxy.sol renamed to contracts/swap/ReserveProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract StableTokenEURProxy is Proxy {

contracts/legacy/proxies/StableTokenBRLProxy.sol renamed to contracts/tokens/StableTokenBRLProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract StableTokenINRProxy is Proxy {

contracts/legacy/proxies/StableTokenCOPProxy.sol renamed to contracts/tokens/StableTokenCOPProxy.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
 contract StableTokenKESProxy is Proxy {

contracts/legacy/proxies/StableTokenEURProxy.sol renamed to contracts/tokens/StableTokenEURProxy.sol

@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.5.13;
 
-import "../../common/Proxy.sol";
+import "../common/Proxy.sol";
 
 /* solhint-disable-next-line no-empty-blocks */
-contract StableTokenPSOProxy is Proxy {
+contract StableTokenPHPProxy is Proxy {
 
 }