build: enable gocritic linter

Running with default set of checks, except disabling the following
- appendAssign: append result not assigned to the same slice (diagnostics check, many false positives)
- captLocal: using capitalized names for local variables (style check, too opinionated)
- commentFormatting: not having a space between `//` and comment text (style check, too opinionated)
- exitAfterDefer: log.Fatalln will exit, and `defer func(){...}(...)` will not run (diagnostics check, to be revisited)
- ifElseChain: rewrite if-else to switch statement (style check, many occurrences and a bit opinionated, to be revisited)
- singleCaseSwitch: should rewrite switch statement to if statement (style check, many occurrences and a bit opinionated, to be revisited)

.golangci.yml

@@ -13,6 +13,7 @@ linters:
     - stylecheck
     - unused
     - misspell
+    - gocritic
     #- prealloc
     #- maligned
   disable-all: true
@@ -98,3 +99,11 @@ linters-settings:
     # Only enable the checks performed by the staticcheck stand-alone tool,
     # as documented here: https://staticcheck.io/docs/configuration/options/#checks
     checks: ["all", "-ST1000", "-ST1003", "-ST1016", "-ST1020", "-ST1021", "-ST1022", "-ST1023"]
+  gocritic:
+    disabled-checks:
+      - appendAssign
+      - captLocal
+      - commentFormatting
+      - exitAfterDefer
+      - ifElseChain
+      - singleCaseSwitch