auto: increment master version to 15.0.64

fix(android/engine): Adjust default OSK landscape size

fix(windows): support Esc key in Download Keyboard dialog

chore(common): iis setup script for dev boxes

fix(web): Always pass kill_browserstack

feat(common): Rust infrastructure

auto: increment master version to 15.0.63

fix(developer): support spaces in regression tests

auto: increment master version to 15.0.62

feat(linux): Integrate with fcitx5

fix(linux): Exclude s390x from package builds for ibus-keyman

Co-authored-by: Marc Durdin <marc@durdin.net>

Fixes #5216.

A `<text>` element in the regression text xml which contained only
whitespace would cause the import to crash as this would be ignored by
the XML parser, leading to a `Null` `nodeValue` for that element. To
solve this, we need to:

1. Use `xml:space="preserve"` attribute on `<text>` elements
2. Update the DTD to allow `xml:space` on `<text>` elements
3. While we are at it, move the DTD from `www.tavultesoft.com` to
   `api.keyman.com`.

See also:
* keymanapp/tavultesoft.com#4
* keymanapp/api.keyman.com#155

This change implements the Keyman side of the fcitx5 integration.
Closes #4910.

Part of #4910.

ibus-keyman depends on keyman-keyboardprocessor which we don't
build for s390x because we currently don't support big-endian.
We only build for the same architectures as keyman-keyboardprocessor.

This change makes the necessary adjustments so that the package build
works with the new `build.sh` script. We no longer can rely on the
automatisms of debhelper. This change also adds a install target
to `build.sh`, and copies some files from the Keyman root directory
to the desktop directory because when package building we only
have access to the files in common/core/desktop. Along the same lines
it removes embedding `build-utils.h` from `build.sh`. Instead we set
the version and tier locally.

Ubuntu 18.04 Bionic only contains Meson 0.45. The build seems
to work with that version, so we partially revert the previous
change that set the minimum version to 0.50.