fix(icons.zsh): update URLs and correct icon mappings

[Locoxella]

uFD03 was removed from nerdfont
Use \uEBD8 (The new Azure logo) for AZURE_ICON
Use \uEBE8 (Azure DevOps) for VCS_GIT_AZURE_ICON
Use \UF023 (Lock) for VPN_ICON
Add \uE7DD Flutter icon
Fix the comment with the URL to open nerdfonts.com cheat-sheet
Update Linux distros and Terraform icon mappings

[Locoxella]

I checked for the icons that exist on the Nerdfonts cheatsheet, searched for them online to confirm they are proper, and tried them on my shell with Nerdfonts.

[romkatv]

What is the output of typeset -p POWERLEVEL9K_MODE in your shell?

What happens if you run p10k configure all the way to the end and again run typeset -p POWERLEVEL9K_MODE?

[Locoxella]

❯ typeset -p POWERLEVEL9K_MODE
typeset POWERLEVEL9K_MODE=nerdfont-complete

Reconfiguring with p10k does not fix the issues.

It is possible to check on https://www.nerdfonts.com/cheat-sheet, as instructed by the comments, to confirm that FD03 has been removed.

The same can be done to check how the new icons look (which I did, and also double checked on my shell just in case)

[Locoxella]

Is there anything else I should be doing on this PR that might still lacking in order for it to be considered?

[romkatv]

The PR addresses several issues. Would it be possible to isolate one, which appears the most like a bug? For example, the description of the issue might look as follows. If you run p10k configure and correctly/truthfully answer all the questions, a specific icon in the prompt does not render, or renders as a different unintended icon. That would be a good description of a problem to tackle.