Set the default PolkaVM stack and heap size values to 128KB. (#441)

Fixes https://github.com/paritytech/contract-issues/issues/149

A few test cases from v2-periphery-polkadot are hitting the PVM stack
limit when the contracts are compiled using resolc version 0.5.0. The
same tests pass if the contracts are compiled with a resolc version that
includes commit:
https://github.com/paritytech/revive/commit/878ca91689b99220f7ffd40df760613b7314de86.

After a brief discussion with @xermicus, we propose to set the default
PolkaVM stack and heap size values to 128KB, since we have already
encountered tests that hit the stack size limit and, without real world
data, it is difficult to determine the optimal values.

docs/user_guide/cli.html

@@ -35,7 +35,7 @@
             const path_to_root = "../";
             const default_light_theme = "light";
             const default_dark_theme = "navy";
-            window.path_to_searchindex_js = "../searchindex-82723808.js";
+            window.path_to_searchindex_js = "../searchindex-4c7bbe7b.js";
         </script>
         <!-- Start loading toc.js asap -->
         <script src="../toc-6f3f265e.js"></script>
@@ -203,7 +203,7 @@
 <li>Increasing the stack size will increase gas costs due to increased startup costs.</li>
 <li>The stack size contributes to the total memory size a contract can use, which includes the contract’s code size.</li>
 </ol>
-<p>Default value: 32768</p>
+<p>Default value: 131072</p>
 <blockquote class="blockquote-tag blockquote-tag-warning">
 <p class="blockquote-tag-title"><svg viewbox="0 0 16 16" width="18" height="18"><path d="M6.457 1.047c.659-1.234 2.427-1.234 3.086 0l6.082 11.378A1.75 1.75 0 0 1 14.082 15H1.918a1.75 1.75 0 0 1-1.543-2.575Zm1.763.707a.25.25 0 0 0-.44 0L1.698 13.132a.25.25 0 0 0 .22.368h12.164a.25.25 0 0 0 .22-.368Zm.53 3.996v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 11a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z"></path></svg>Warning</p>
 <p>If the contract uses more stack memory than configured, it will compile fine but eventually revert execution at runtime!</p>
@@ -215,7 +215,7 @@
 <p>You are incentivized to keep this value as small as possible:
 1.Increasing the heap size will increase startup costs.
 2.The heap size contributes to the total memory size a contract can use, which includes the contract’s code size</p>
-<p>Default value: 65536</p>
+<p>Default value: 131072</p>
 <blockquote class="blockquote-tag blockquote-tag-warning">
 <p class="blockquote-tag-title"><svg viewbox="0 0 16 16" width="18" height="18"><path d="M6.457 1.047c.659-1.234 2.427-1.234 3.086 0l6.082 11.378A1.75 1.75 0 0 1 14.082 15H1.918a1.75 1.75 0 0 1-1.543-2.575Zm1.763.707a.25.25 0 0 0-.44 0L1.698 13.132a.25.25 0 0 0 .22.368h12.164a.25.25 0 0 0 .22-.368Zm.53 3.996v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 11a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z"></path></svg>Warning</p>
 <p>If the contract uses more heap memory than configured, it will compile fine but eventually revert execution at runtime!</p>