Add Python installation guide and Cotainr documentation

[Chroxvi]

The main part of this PR is:

• Adding a new page on "Installing Python packages" on LUMI, giving an overview of recommended and discouraged options for installing Python packages on LUMI. This is includes a condensed version of the content in the stale #24. The intention is to close #24 as superseded by this PR.
• Updating the existing documentation on pulling and building Singularity/Apptainer containers on LUMI to include a description of the use of cotainr to build containers on LUMI (primarily for Conda/pip environments).
• Updating the "container wrapper" documentation to reflect the more general purpose nature of the tool - not just a Conda/pip wrapper. This includes a tentative change of its name to "Tykky installation wrapper" - please suggest a better name, if you have one! See #110 for more discussion about the motivation for this change.

Additionally, this PR also includes:

• Minor changes and clean-ups to various pages throughout the documentation mentioning do's and don'ts related to Conda, pip, or Python. These now link to the new "Installing Python packages" page.
• A fix for #60

Open questions:

• [x] Is "Tykky installation wrapper" the right new name for what is currently known as the "LUMI container wrapper".
• [x] If we rename the "LUMI container wrapper" in the docs, how do we handle the transition of the lumi-container-wrapper module to a new name?

[Chroxvi]

@hdrei I have updated the PR to address your review comments. Please see check if all your concerns have been address.

• I have done a major rework of the software overview page. I like the new version a lot, but I am also a bit concerned about the overlap with the content in https://docs.lumi-supercomputer.eu/runjobs/lumi_env/Lmod_modules/ and https://docs.lumi-supercomputer.eu/runjobs/lumi_env/softwarestacks/.
• I have changed the structure of the Python packages installation page to more aggressively make use of sections as you suggested. I like the change. Initially, I also thought about creating a table as an alternative. However, I felt it would probably be difficult to make it easily comprehensible given the somewhat limited formatting options, markdown files provide.

[Chroxvi]

@Nortamo, this PR makes some changes to the description of Tykky in the LUMI docs. Please chime in if you think some of it is inaccurate or otherwise needs to be changed.

[Nortamo]

@Nortamo, this PR makes some changes to the description of Tykky in the LUMI docs. Please chime in if you think some of it is inaccurate or otherwise needs to be changed.

Hi, Sorry for the late reply I was away a week. Changes look good to me. New name is also sensible. Great work!

[Chroxvi]

@Nortamo No problem! Thanks a lot for taking your time to look at this.