Move shellcheck config to dedicated rc file (#825)

# Summary
This allows invoking ShellCheck outside of the pre-commit hook, [such as
in the VSCode linter
extension](https://marketplace.visualstudio.com/items?itemName=timonwong.shellcheck).

## Proof of Work

<!-- Enter your proof that it works here.-->

## Checklist

- [ ] Have you linked a jira ticket and/or is the ticket in the title?
- [ ] Have you checked whether your jira ticket required DOCSP changes?
- [ ] Have you added changelog file?
    - use `skip-changelog` label if not needed
- refer to [Changelog files and Release
Notes](https://github.com/mongodb/mongodb-kubernetes/blob/master/CONTRIBUTING.md#changelog-files-and-release-notes)
section in CONTRIBUTING.md for more details

Signed-off-by: Yavor Georgiev <yavor.georgiev@mongodb.com>

Author: fealebenpae

.pre-commit-config.yaml

@@ -117,7 +117,6 @@ repos:
     rev: v0.10.0
     hooks:
       - id: shellcheck
-        args: [-e, SC2154, -e, SC2153, -e, SC1091, -e, SC1090, -e, SC2148, -o, require-variable-braces, -P, scripts]
         exclude: |
           (?x)^(
             vendor/.*|

.shellcheckrc

@@ -0,0 +1,8 @@
+# Disable specific checks
+disable=SC2154,SC2153,SC1091,SC1090,SC2148
+
+# Enable optional checks
+enable=require-variable-braces
+
+# Add scripts directory to source path
+source-path=scripts