Change mail logo to material design icon

[GretaD]

To do

• [x] Change all the mail icons to img folder
• [ ] Attribution

Fixes https://github.com/nextcloud/mail/issues/6498

[jancborchardt]

All changed to the Material Design icon. While working on it, especially generating out the png versions, I was thinking which files of these are actually still necessary to manually create and which ones are generated by our theming. @juliushaertl do you know, and/or is this documented somewhere in the app dev docs?

[juliusknorr]

All changed to the Material Design icon. While working on it, especially generating out the png versions, I was thinking which files of these are actually still necessary to manually create and which ones are generated by our theming. @juliushaertl do you know, and/or is this documented somewhere in the app dev docs?

We still need them for cases where ImageMagick is not available or limited. E.g. it is quite common these days to have disable SVG reading by imagemagick in distributions by default, as this may bring additional risk with malicious files.

[ChristophWurst]

Do we even use the icons changed with the latest commit https://github.com/nextcloud/mail/pull/6944/commits/505d682991a4ac55d15bc7750236a76b62a561b6? I think those are unused with your recent changes that dropped all custom icons.

[GretaD]

should all *.svg and *.png be commited / merged?

im not sure if i understand what refer with all, but in other apps we only do the svg, if the png is the same icon.

[jancborchardt]

@ChristophWurst no, they are not used anymore and can be removed. @GretaD you wanted to remove them right?