build(types): --clean option for package isolation

The postpack of a previous package only cleans up files in that package. Its prepack may build files in other packages that it doesn't clean up.
The remants were causing errors like:
```
> @agoric/governance@0.10.4-dev-5988fad.0 prepack /home/runner/work/agoric-sdk/agoric-sdk/packages/governance
> echo "export {}; " | cat - src/types-ambient.js > src/types.js && tsc --build tsconfig.build.json

error TS5055: Cannot write file '/home/runner/work/agoric-sdk/agoric-sdk/packages/ERTP/exported.d.ts' because it would overwrite input file.
```
(in 'https://github.com/Agoric/agoric-sdk/actions/runs/6346051963/job/17239010386?pr=8410'\)

This makes the build clean up files in the way.

packages/ERTP/package.json

@@ -9,7 +9,7 @@
   },
   "scripts": {
     "build": "exit 0",
-    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build tsconfig.build.json",
+    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build --clean tsconfig.build.json",
     "postpack": "git clean -f '*.d.ts*' src/types.js",
     "test": "ava",
     "test:c8": "c8 $C8_OPTIONS ava",

packages/governance/package.json

@@ -10,7 +10,7 @@
   "scripts": {
     "build": "yarn build:bundles",
     "build:bundles": "node ./scripts/build-bundles.js",
-    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build tsconfig.build.json",
+    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build --clean tsconfig.build.json",
     "postpack": "git clean -f '*.d.ts*' src/types.js",
     "test": "ava",
     "test:c8": "c8 $C8_OPTIONS ava --config=ava-nesm.config.js",

packages/notifier/package.json

@@ -9,7 +9,7 @@
   },
   "scripts": {
     "build": "exit 0",
-    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build tsconfig.build.json",
+    "prepack": "echo \"export {}; \" | cat - src/types-ambient.js > src/types.js && tsc --build --clean tsconfig.build.json",
     "postpack": "git clean -f '*.d.ts*' src/types.js",
     "test": "ava",
     "test:c8": "c8 $C8_OPTIONS ava --config=ava-nesm.config.js",

packages/zoe/package.json

@@ -10,7 +10,7 @@
   "scripts": {
     "build": "yarn build:bundles",
     "build:bundles": "node scripts/build-bundles.js",
-    "prepack": "echo \"export {}; \" | cat - tools/types-ambient.js > tools/types.js && tsc --build tsconfig.build.json",
+    "prepack": "echo \"export {}; \" | cat - tools/types-ambient.js > tools/types.js && tsc --build --clean tsconfig.build.json",
     "postpack": "git clean -f '*.d.ts*' tools/types.js",
     "test": "ava --verbose",
     "test:c8": "c8 $C8_OPTIONS ava --config=ava-nesm.config.js",