fix: `INSTALLATION FAILED: Can't evaluate field ApiVersion

[fResult]

From the issue #70.
Fixed an error INSTALLATION FAILED: Can't evaluate field ApiVersion in type interface {}.

After updating code result:

P.S. Indeed, if it can be more than 1 specific key, we might be able to do something like this.

// NOTE: Some keys are not just a PascalCase, they can be...
const SPECIAL_KEY_REPLACEMENT: Record<string, string> = {
    apiVersion: 'APIVersion',
    SpecialKey1: 'SPECIALKey1',
    SpecialKey2: 'SPECIALKey2',
    // More special key goes here...
}

export class ChartCompletionItemProvider implements vscode.CompletionItemProvider {
    .
    .
    private getCompletionItemList(currentKey: any): vscode.CompletionItem[] {
        const keys = [];
        for (const key in currentKey) {
            switch (typeof currentKey[key]) {
                .
                .
                case 'number':
                    // NOTE: APIVersion is a special case, as it is not camelCase for `{{ .Chart.APIVersion }}`.
                    const specialText = SPECIAL_KEY_REPLACEMENT[key]
                    const completionText = specialText ?? key.charAt(0).toUpperCase() + key.slice(1);
                    const valueItem = new vscode.CompletionItem(completionText, vscode.CompletionItemKind.Field);
                    valueItem.detail = currentKey[key].toString();
                    keys.push(valueItem);
                    break;
            }
        }
    }
}