feat(installer): fix styling to scale according to the name width

[akalipetis]

Example output for Platform and Upsun:

➜  cli INSTALL_METHOD=raw bash installer.sh
+------------------------------------------------+
|                                                |
|   Upsun (formerly Platform.sh) CLI Installer   |
|                                                |
+------------------------------------------------+

Checking environment
  [*] Your kernel (darwin) is supported
  [*] Your architecture (arm64) is supported
  [*] Using raw install method
  [*] cURL is installed
  [*] Using GitHub auth from the gh CLI
  [*] No version specified, using latest (5.6.0)
  [*] Gzip is installed
  [*] sha1sum is installed
  [*] /Users/akalipetis/.local/bin is in $PATH

Target directories
  Binary will be installed in /Users/akalipetis/.local/bin

Downloading the Upsun (formerly Platform.sh) CLI
  Downloading https://github.com/platformsh/cli/releases/download/5.6.0/platform_5.6.0_darwin_all.tar.gz
  Uncompressing archive
  Making the binary executable
  Installing the binary under /Users/akalipetis/.local/bin

+-------------------------------------------------------------------+
|                                                                   |
| Upsun (formerly Platform.sh) CLI has been installed successfully. |
|                                                                   |
+-------------------------------------------------------------------+

What's next?
  To use the CLI, run: platform

Useful links:
  CLI introduction: https://docs.upsun.com/get-started/introduction.html#cli

Thank you for using Upsun (formerly Platform.sh)!
➜  cli git:(main) ✗ 
➜  cli git:(main) ✗ VENDOR=upsun INSTALL_METHOD=raw bash installer.sh
+------------------------------------------------+
|                                                |
|              Upsun CLI Installer               |
|                                                |
+------------------------------------------------+

Checking environment
  [*] Your kernel (darwin) is supported
  [*] Your architecture (arm64) is supported
  [*] Using raw install method
  [*] cURL is installed
  [*] Using GitHub auth from the gh CLI
  [*] No version specified, using latest (5.6.0)
  [*] Gzip is installed
  [*] sha1sum is installed
  [*] /Users/akalipetis/.local/bin is in $PATH

Target directories
  Binary will be installed in /Users/akalipetis/.local/bin

Downloading the Upsun CLI
  Downloading https://github.com/platformsh/cli/releases/download/5.6.0/upsun_5.6.0_darwin_all.tar.gz
  Uncompressing archive
  Making the binary executable
  Installing the binary under /Users/akalipetis/.local/bin

+------------------------------------------------+
|                                                |
|   Upsun CLI has been installed successfully.   |
|                                                |
+------------------------------------------------+

What's next?
  To use the CLI, run: upsun

Useful links:
  CLI introduction: https://docs.upsun.com/get-started/introduction.html#cli

Thank you for using Upsun!

[Copilot]

Pull Request Overview

This PR enhances the installer script's visual presentation by making the ASCII art tables dynamically scale based on the vendor name length rather than using fixed-width formatting.

• Adds two new functions (create_table_line and create_table) to generate dynamic-width ASCII art tables
• Replaces hardcoded table formatting in intro, outro, and error functions with dynamic table generation
• Updates table width calculation to accommodate different vendor name lengths (e.g., "Upsun CLI Installer" vs "Upsun (formerly Platform.sh) CLI Installer")

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