Add .gitreview file

`git-review` is a command line tool for interacting with Gerrit.
Some IDEs offer support for this tool, either natively or through
plugins. The tool relies on a configuration file, .gitreview. Adding
this configuration file to our repositories simplifies initial setup
for contributors that use the tool directly or through their IDE of
choice.

The configuration file adds a remote called 'gerrit'. This is the
default for the tool, and also the name set for
codereview.qt-project.org by Qt's `init-repository` script. Thus,
the configuration should work seamlessly alongside other repository
helpers.

As the file format doesn't seem to be designed with comments in mind,
add it to the other version control system exemptions in REUSE.toml.

Task-number: QTBUG-132604
Pick-to: 6.9 6.8
Change-Id: I5b3fd33b6c43d28c9268ad2cc3f43214d812d8c7
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>

.gitreview

@@ -0,0 +1,4 @@
+[gerrit]
+host=codereview.qt-project.org
+project=qt/qtgrpc
+defaultbranch=dev

REUSE.toml

@@ -21,7 +21,7 @@ SPDX-FileCopyrightText = "Copyright (C) 2024 The Qt Company Ltd."
 SPDX-License-Identifier = "BSD-3-Clause"
 
 [[annotations]]
-path = [".tag", "**/.gitattributes", "**.gitignore"]
+path = [".tag", "**/.gitattributes", "**.gitignore", "**/.gitreview"]
 comment = "version control system. Licensed as build system"
 precedence = "closest"
 SPDX-FileCopyrightText = "Copyright (C) 2024 The Qt Company Ltd."