Fix installation to work with bash and all versions of shell

[commit111]

Description

Note: A better version of this is #878

Replaced the Shell installation . <(curl -Ls https://s.defang.io/install) with eval "$(curl -Ls https://s.defang.io/install)" to fix the issue of process substitution not being available on older versions of Bash.

There was discussion on other alternatives:

• . /dev/stdin <<<"$(curl -Ls https://s.defang.io/install)" - good but a little long-looking
• curl -Ls https://s.defang.io/install | sh - cannot use defang immediately without refreshing after 1st install

If you have any opinion on which command to use, please comment below.

Linked Issues

Fixes #631
Updated /defang-docs repo DefangLabs/defang-docs#115
Updated /samples repo DefangLabs/samples#258
Updated /docs-chatbot repo DefangLabs/docs-chatbot#19

Checklist

• I have performed a self-review of my code
• I have added appropriate tests
• I have updated the Defang CLI docs and/or README to reflect my changes, if necessary

[lionello]

The reason we used . <(curl …) vs curl … | sh is that in the latter case you won't be able to run defang right after the 1st installation, since the installer won't be able to change PATH of the calling shell.

[lionello]

Awesome! Can you check the other repos as well (defang-docs etc.)?