namingConvention shouldn't affect documentVariablePrefix/Suffix

### Which packages are impacted by your issue?

@graphql-codegen/visitor-plugin-common

### Describe the bug

`namingConvention` is supposed to affect **type names** (`typeNames`) and **enum value names** (`enumValues`) only.

However, **variable names** created with `typed-document-node` for operations are also affected by the option, which is not expected.

### Your Example Website or App

https://stackblitz.com/edit/github-xc1bjj?file=types.ts

### Steps to Reproduce the Bug or Issue

In the Stackblitz example, set the `namingConvention` and run `npm run generate` to test the following scenarios:

## `namingConvention: { typeNames: "change-case-all#pascalCase" }` (default)

```ts
export const GqluserDocument = … // should be [g]ql[U]serDocument
export const GqldeleteUserDocument = … // should be [g]ql[D]eleteUserDocument
export const GqlDeleteUserUppercaseDocument = … // should be [g]qlDeleteUserUppercaseDocument
export type MutationDeleteUserArgs = … // good, as expected
export type QueryUserArgs = … // good, as expected
```

## `namingConvention: { typeNames: "keep" }`

```ts
export const gqluserDocument = … // bad, but as expected
export const gqldeleteUserDocument = … // bad, but as expected
export const gqlDeleteUserUppercaseDocument = … // good, as expected
export type MutationdeleteUserArgs = … // bad, but as expected?
export type QueryuserArgs = … // bad, but as expected?
```

### Expected behavior

With `namingConvention: { typeNames: "change-case-all#pascalCase" }` (default) I expect:

- Types start uppercase.
- Explicit prefixes and suffixes remain exactly as defined. I chose a lowercase prefix here because these are used for variable names, not type names.

```ts
export const gqlUserDocument = … // good, as expected
export const gqlDeleteUserDocument = … // good, as expected
export const gqlDeleteUserUppercaseDocument = … // good, as expected
export type MutationDeleteUserArgs = … // good, as expected
export type QueryUserArgs = … // good, as expected
```

**It's impossible to achieve that consistency easily** with the currently available config options. Either the `gql` prefix starts uppercase or the `…Args` types are lowercase after `Mutation` and `Query`. The only alternative is to write my own conversion function that checks if the string (which can be either a type or a variable name) starts with my prefix and then treat that in a special way.

Also, I need to write all operation names in uppercase in the GraphQL document in order to achieve `gqlUserDocument` instead of `gqluserDocument`, which seems odd.

--

This happens because `documentVariablePrefix/Suffix` are passed as `prefix/suffix` to the `convertName` and thus converted as if they're part of the type name. They should instead be applied **after** converting the type name.

https://github.com/dotansimha/graphql-code-generator/blob/39e6e80903e325eb0ddf040389c214428c9362e9/packages/plugins/other/visitor-plugin-common/src/client-side-base-visitor.ts#L743-L749

### Screenshots or Videos

_No response_

### Platform

- OS: macOS, Linux
- NodeJS: 22.2.0, 18.20.3
- `graphql` version: 16.8.1, 16.2.0
- `@graphql-codegen/cli`: 5.0.2
- `@graphql-codegen/near-operation-file-preset`: 3.0.0
- `@graphql-codegen/typed-document-node`: 5.0.7
- `@graphql-codegen/typescript`: 4.0.7
- `@graphql-codegen/typescript-operations`: 4.2.1
- `@graphql-typed-document-node/core`: 3.2.0

### Codegen Config File

```ts
import { CodegenConfig } from '@graphql-codegen/cli';

const config: CodegenConfig = {
config: {
documentVariablePrefix: 'gql',
namingConvention: {
typeNames: 'change-case-all#pascalCase',
},
},
schema: 'schema.graphql',
documents: 'document.graphql',
generates: {
'types.ts': {
plugins: ['typed-document-node', 'typescript', 'typescript-operations'],
},
},
};

export default config;
```

### Additional context

### Schema
```gql
type Mutation {
deleteUser(id: ID!): Boolean
}

type Query {
user(id: ID!): User!
}

type User {
id: ID!
username: String!
email: String!
}
```

### Document
```gql
query user {
user(id: 1) {
id
username
email
}
}

mutation deleteUser($id: ID!) {
deleteUser(id: $id)
}

mutation DeleteUserUppercase($id: ID!) {
deleteUser(id: $id)
}
```