Fix: UI layout issues

[devvaannsh]

This PR is to fix all the UI layout issues. Please refer to this issue

1. Fixed profile button text not centralized issue - also reduced the font-size a bit because the font was too large as per the button size

Before

After

2. Added a Cancel button in add-snippets-panel
3. Increased the Custom Snippets panel minimum size so that the buttons always remain visible
4. Fix icons alignment
5. Add checkmark in the menu item when the panel is open
6. In the add snippet & edit snippet panel, move the content a bit towards right to maintain hierarchy structure

Before

After

7. Enable/Disable reset button in the Edit Snippet panel, as and when required
8. Earlier we expected users to write file extension in strict format that is .js, .css, .html like every file extension should start with a dot and it should be separated with commas, but now users can write as they want. anything will work. For ex js, css, html will work, js, .css.html , js css html will work too.
9. Instead of saving the snippets in preferences manager, we now save it in file storage - this change was important because otherwise prefs file got too lengthy with many snippets and it became unusable.

[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[abose]

LGTM . Merging.
Thanks for the changes @devvaannsh