Progress a bit on self-building for Schildichat

This is related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3831

It:

- adds some missing variables
- version variable to branch variable conversion

While it improves the situation, it still doesn't result in a working
self-building feature, because:

- cloning a repository containing submodules requires special care,
  as described here
  (https://github.com/SchildiChat/schildichat-desktop/blob/c03ef20e5dc0a88cec479c9711d9941aba48ab97/README.md#initial-build-setup)

- we likely better clone a specific repository version from the very beginning, instead of trying to change subsequently (and having to re-initilize submodules)
  though that's very different than what we're doing elsewhere and is likely very wasteful

- we can't just build a `Dockerfile`, we need to invoke `make setup` (`./setup.sh`)

- it's likely that the `docker-src` directory is not reusable across
  versions or may require special handling to clean up files, etc.

roles/custom/matrix-client-schildichat/defaults/main.yml

@@ -4,6 +4,12 @@
 matrix_client_schildichat_enabled: true
 
 matrix_client_schildichat_container_image_self_build: false
+matrix_client_schildichat_container_image_self_build_repo: "https://github.com/SchildiChat/schildichat-desktop.git"
+matrix_client_schildichat_container_image_self_build_version: "{{ 'lite' if matrix_client_schildichat_version == 'latest' else ('v' + matrix_client_schildichat_version) }}"
+# Controls whether to patch webpack.config.js when self-building, so that building can pass on low-memory systems (< 4 GB RAM):
+# - https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1357
+# - https://github.com/element-hq/element-web/issues/19544
+matrix_client_schildichat_container_image_self_build_low_memory_system_patch_enabled: "{{ ansible_memtotal_mb < 4096 }}"
 
 # renovate: datasource=docker depName=ghcr.io/etkecc/schildichat-web
 matrix_client_schildichat_version: 1.11.36-sc.3
@@ -12,7 +18,7 @@ matrix_client_schildichat_docker_image_name_prefix: "{{ 'localhost/' if matrix_c
 matrix_client_schildichat_docker_image_force_pull: "{{ matrix_client_schildichat_docker_image.endswith(':latest') }}"
 
 matrix_client_schildichat_data_path: "{{ matrix_base_data_path }}/client-schildichat"
-matrix_client_schildichat_docker_src_files_path: "{{ matrix_client_schildichat_data_path }}/docker-src"
+matrix_client_schildichat_container_src_files_path: "{{ matrix_client_schildichat_data_path }}/docker-src"
 
 # The base container network
 matrix_client_schildichat_container_network: ''