Use plugin architecture to download phylotrees from remote repository

This pull request uses the following repository to host a json file with all available trees: https://github.com/genepi/haplogrep-trees/blob/main/trees.json

Version 15 of phyoltree-rcrs is available in this repository: https://github.com/genepi/phylotree-rcrs. It contains a Makefile to build the final target zip.

To use a tree from the repository add the following to haplogrep3.config:

phylotrees:
  - "phylotree-rcrs@15.0"

or use the install-tree command:

haplogrep install-tree phylotree-rcrs@15.0

Note: it is still possible to set the path to the yaml file directly:

phylotrees:
  - data/trees/phylotree/16/tree.yaml
  - "phylotree-rcrs@15.0"

Open tasks:

[x] Add install-tree command to add tree to config file and to install it
[x] Add version 16.0 and 17.0 to https://github.com/genepi/phylotree-rcrs. And create releases and register them in repository haplogrep-trees
[x] Add repository phylotree-fu. Add tree, create releases and register it in repository haplogrep-trees
[x] Add repository phylotree-rsrs. Add tree, create releases and register it in repository haplogrep-trees
[x] Update testcases to use trees from remote repository and remove all trees from data folder.
[x] Improve trees combobox by grouping trees by reference name. read name from fasta file? or own property in yaml?

rCRS (Human mtDNA hg38)
  Phylotree 17 - Forensic Update 
  PhyloTree 17
  PhyloTree 16
  PhyloTree 15
RSRS (Human mtDNA)
    PhyloTree 17

genepi / haplogrep3