Dual-license under Apache 2.0 and MIT

Most of fluent-rs is already dual-licensed.  This crate is not, which
can make it harder for GPL-2-only projects to use fluent-rs.

Fix that by allowing use under MIT lincense. All (or almost all?)
nontrivial contributions seem to be from the same author, so this should
be easy?

Ref: projectfluent/fluent-rs#34
Ref: fish-shell/fish-shell#11928

See also the previous discussion of relicensing fluent-rs where the same
change was made to the other crates:

Ref: https://bugzilla.mozilla.org/show_bug.cgi?id=1408992

Co-authored-by: Eemeli Aro <eemeli@gmail.com>
Signed-off-by: Caleb Maclennan <caleb@alerque.com>
Signed-off-by: Colin Rofls <colin@cmyr.net>
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
Signed-off-by: Zibi Braniecki <zibi@amazon.com>

Author: 2 people

Cargo.toml

@@ -8,7 +8,7 @@ authors = [
 	"Zibi Braniecki <zibi@unicode.org>"
 ]
 homepage = "http://projectfluent.org/"
-license = "Apache-2.0"
+license = "Apache-2.0 OR MIT"
 repository = "https://github.com/projectfluent/fluent-langneg-rs"
 readme = "README.md"
 categories = ["internationalization", "localization"]

LICENSE renamed to LICENSE-APACHE

@@ -0,0 +1,19 @@
+Copyright Mozilla Foundation
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.