Add search and toggle NS in navigator panel

### Description

I have 23 years of experience in programming.
The only problem is the navigator panel in the IDE.
1. You need to add a search field to filter function names. There are more than a hundred functions in the class, because the architecture of the platform is built in, it is difficult to search for the necessary functions and switch between them. I believe that 10% of developers face this.
2. You need to add the "Namespace" button to the filter panel of the navigator panel.
3. Add 'CSS' button to the filter panel of the navigator panel.
4. Add 'HTML' button to the filter panel of the navigator panel.
5. Add 'JavaScript' button to the filter panel of the navigator panel.

If the functions are nested, then the filter field will filter so that the parent functions (classes) are displayed if the nested functions have the desired pattern.

**I am sure that the first 2 items menu are very important.**

### For the redesign, you can remove the FILTERS label, but add the FILTERS text to the search field as a PLACEHOLDER. This default text will indicate that this panel is a filter.

In addition, it can be assumed that the selected current function will differ from the filter pattern, i.e. it will not fit the search criteria.
In this case, I suggest, among other things, always display the currently selected function, even if it does not fit the function.

```JS
PHP (JS, CSS), Project: Plugin JoomShopping with Joomla, NetBeans 26, OS: VanillaOS 2.0
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### Use case/motivation

_No response_

### Related issues

_No response_

### Are you willing to submit a pull request?

No

No implementation files or tests are named. Start by locating the NetBeans navigator panel and its existing filter controls, then determine how nested functions and the current selection are represented. Done means the panel supports the requested search and Namespace, CSS, HTML, and JavaScript filters, including the stated nested-function and current-selection behavior.

Written by the indexing model from the issue text.