* DevEnv: updates webpack 4.29.6 -> 4.41.5

* DevEnv: updates webpack-cli 3.2.3 -> 3.3.10

* DevEnv: updates webpack-dev-server 3.2.1 -> 3.10.3

* DevEnv: updates terser-webpack-plugin 1.2.3 -> 2.3.4

* DevEnv: updates webpack-bundle-analyzer 3.3.2 -> 3.6.0

* DevEnv updates webpack-merge 4.2.1 -> 4.2.2

* DevEnv: updates clean-webpack-plugin 2.0.0 -> 3.0.0

* DevEnv: updates file-loader 3.0.1 -> 5.0.2

* DevEnv: updates css-loader 2.1.1 -> 3.4.2

* DevEnv: updates sass-loader 7.1.0 -> 8.0.2

* DevEnv: updates style-loader 0.23.1 -> 1.1.3

* DevEnv: updates fork-ts-checker-webpack-plugin 1.0.0 -> 4.0.3

* DevEnv: updates optimize-css-assets-webpack-plugin 5.0.1 -> 5.0.3

* DevEnv: updates mini-css-extract-plugin 0.5.0 -> 0.9.0

* DevEnv: updates @cypress/webpack-preprocessor 4.1.1 -> 4.1.3 in grafana-e2e package

* DevEnv: updates @types/webpack 4.4.34 -> 4.41.7 in grafana-toolkit package

* DevEnv: updates copy-webpack-plugin 5.0.3 -> 5.1.1 in grafana-toolkit package

* DevEnv: updates terser-webpack-plugin 1.3.0 -> 2.3.4 in grafana-toolkit package

* DevEnv: updates webpack 4.35.0 -> 4.41.5 in grafana-toolkit package