Improve ClientSettings parsing

[dani-garcia]

Type of change

- [x] Bug fix
- [ ] New feature development
- [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

Remove null fields from the ClientSettings input, as serde deserializes the object correctly if the fields are unset, but not if they are explicitly null

[bitwarden-bot]

Checkmarx One – Scan Summary & Details – 8c251fde-80be-4fea-b348-7eb3488eb98c

New Issues

Severity	Issue	Source File / Package	Checkmarx Insight
	Reflected_XSS	/languages/kotlin/app/src/main/java/com/bitwarden/myapplication/MainActivity.kt: 294	Attack Vector
	Unchecked_Input_for_Loop_Condition	/languages/kotlin/app/src/main/java/com/bitwarden/myapplication/MainActivity.kt: 294	Attack Vector

Fixed Issues

Severity	Issue	Source File / Package
	Reflected_XSS	/languages/kotlin/app/src/main/java/com/bitwarden/myapplication/MainActivity.kt: 115
	Unchecked_Input_for_Loop_Condition	/languages/kotlin/app/src/main/java/com/bitwarden/myapplication/MainActivity.kt: 115

[Hinton]

Suggesting #432 instead of this. We can revisit if we find more needs for this.