Oops, Debian 11 is bullseye, not buster

Update installation instructions for Debian

Ignore .map and TEST-*.xml files

Ignore all generated linker .map files from robot directory
and all TEST-*.xml files from xml directory.

Fix the test case assertion exception wording in the manual.

The report and the fix from Rod Kay, thanks!

Update versions in README for 2.9.

Fedora is now at version 35 and Debian at version 11.

Move basic.robot to tests directory.

Create new directory 'robot/tests' for all the Robot Framework tests
and move the existing tests there.

Then we can run the tests with command 'robot tests'.

Move robot test executables to bin dir.

Move the test executables generated for the Robot Framework
tests to the robot/test_sources/bin directory.

Mention Git mirrors in README.md.

Change gnat-8 to gnat-10 in debian/stable build setup.

Sourcehut updated their debian/stable to bullseye,
which has gnat-10 package instead of gnat-8.

Add .editorconfig file.

Ada files use 3 spaces, Makefile tabs,
unix style newlines.

Mention SPDX identifier addition in NEWS.txt.

Don't mention Fedora version in install instructions

Increase version to 2.9 in NEWS.txt.

While there, mention the Alire package manager configuration
files from Michael Rohan.

Increase version to 2.9 everywhere.

As done with Alire project file, increate the version to 2.9
in the documentation and Linux (Fedora) GNAT project files.

Increase Library_Version to 2.9.0 in ahven_alire.gpr.

Merge heads.

Specify Library_Interface in ahven_alire projet file.

As we have some extra files in src directory, specify
the ones we actually use to avoid unnecessary compilations.

Eliminate parameter Severity from Report_Not_Ok function.

This allows us to get rid of one GNAT warning about
unused parameter.

Add Alire packaging support files

Added the top level alire.toml file to define Ahven as an Alire package
and the gnat/ahven_alire.gpr project file to build the library using the
defaults generated by Alire (style checks are disabled by default).

Improve control/tap/tester.pl a little.

Add ability to give the test runner as an argument.
Also do some sanity checks and return status based
on the test execution status.