Added increment and decrement actions (#2236)

Fixes #2192

## Checklist

- [x] I have added
[tests](https://www.cursorless.org/docs/contributing/test-case-recorder/)
- [x] I have updated the
[docs](https://github.com/cursorless-dev/cursorless/tree/main/docs) and
[cheatsheet](https://github.com/cursorless-dev/cursorless/tree/main/cursorless-talon/src/cheatsheet)
- [x] I have not broken the cheatsheet

---------

Co-authored-by: Pokey Rule <[email protected]>

Author: 2 people

src/spoken_forms.json

@@ -14,6 +14,7 @@
       "comment": "toggleLineComment",
       "copy": "copyToClipboard",
       "crown": "scrollToTop",
+      "decrement": "decrement",
       "dedent": "outdentLine",
       "define": "revealDefinition",
       "drink": "editNewLineBefore",
@@ -25,6 +26,7 @@
       "give": "deselect",
       "highlight": "highlight",
       "hover": "showHover",
+      "increment": "increment",
       "indent": "indentLine",
       "inspect": "showDebugHover",
       "join": "joinLines",