Add .git-blame-ignore-revs with linter-related mass change commits (#2000)

This file is automatically recognized by GitHub. For git to recognized
it, run:

`git config blame.ignoreRevsFile .git-blame-ignore-revs`

## Tests
Run 'git blame' with and without this option.

Compare view on Github

https://github.com/databricks/cli/blame/2e018cf/libs/git/reference_test.go

https://github.com/databricks/cli/blame/denis.bilenko/ignore-linter-commits/libs/git/reference_test.go

Author: denik

.git-blame-ignore-revs

@@ -0,0 +1,8 @@
+# Enable gofumpt and goimports in golangci-lint (#1999)
+2e018cfaec200a02ee2bd5b389e7da3c6f15f460
+
+# Enable errcheck everywhere and fix or silent remaining issues (#1987)
+8d5351c1c3d7befda4baae5d6adb99367aa50b3c
+
+# Add error checking in tests and enable errcheck there (#1980)
+1b2be1b2cb4b7909df2a8ad4cb6a0f43e8fcf0c6