Merge branch 'master' into rugvip/minmax

.changeset/brave-pugs-fold.md

@@ -0,0 +1,5 @@
+---
+'@backstage/test-utils': patch
+---
+
+Add new `MockConfigApi` as a more discoverable and leaner method for mocking configuration.

.changeset/fair-bikes-scream.md

@@ -0,0 +1,28 @@
+---
+'@backstage/cli': minor
+---
+
+ESLint upgraded to version 8 and all it's plugins updated to newest version.
+
+If you use any custom plugins for ESLint please check compatibility.
+
+```diff
+-    "@typescript-eslint/eslint-plugin": "^v4.33.0",
+-    "@typescript-eslint/parser": "^v4.28.3",
++    "@typescript-eslint/eslint-plugin": "^5.9.0",
++    "@typescript-eslint/parser": "^5.9.0",
+-    "eslint": "^7.30.0",
++    "eslint": "^8.6.0",
+-    "eslint-plugin-import": "^2.20.2",
+-    "eslint-plugin-jest": "^24.1.0",
+-    "eslint-plugin-jsx-a11y": "^6.2.1",
++    "eslint-plugin-import": "^2.25.4",
++    "eslint-plugin-jest": "^25.3.4",
++    "eslint-plugin-jsx-a11y": "^6.5.1",
+-    "eslint-plugin-react": "^7.12.4",
+-    "eslint-plugin-react-hooks": "^4.0.0",
++    "eslint-plugin-react": "^7.28.0",
++    "eslint-plugin-react-hooks": "^4.3.0",
+```
+
+Please consult changelogs from packages if you find any problems.

.changeset/quiet-carpets-shake.md

@@ -0,0 +1,7 @@
+---
+'@backstage/plugin-kubernetes': patch
+'@backstage/plugin-pagerduty': patch
+'@backstage/plugin-splunk-on-call': patch
+---
+
+Clean up emptystate.svg image, removing wrong white artifact from the background

.changeset/rotten-olives-shop.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Update `config/eslint.js` to forbid imports of `@material-ui/icons/` as well.

.changeset/tender-cars-look.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': patch
+---
+
+Bump `testcontainers` dependency to version `8.1.2`