fix: enable lll linter and format long function signatures

Previously lll linter was configured to .golangci.yml but with
a typo in the directive ('linter-settings', not 'linters-settings').

Enable line length linter and fix long lines by breaking function
signatures across multiple lines in exec.go, attach.go, and resource.go.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

.golangci.yml

@@ -1,7 +1,3 @@
-linter-settings:
-  lll:
-    line-length: 200
-
 timeout: 10m
 
 issues:
@@ -30,8 +26,11 @@ linters:
     - gosec
     - copyloopvar # Checks for pointers to enclosing loop variables
     - tenv # Detects using os.Setenv instead of t.Setenv since Go 1.17
+    - lll
 
 linters-settings:
   gosec:
     excludes:
       - G304 # Potential file inclusion via variable
+  lll:
+    line-length: 200