stbt lint: Add checker stbt-frame-object-property-single-frame

[drothlis]

FrameObject properties must process a single frame; functions like "stbt.wait_for_match" retrieve additional frames from the device-under-test.

Suggested during code review of #580.

TODO:

• Figure out why pylint is reporting Undefined variable 'wait_for_match' (see comment).

[drothlis]

The failure in test_that_stbt_lint_checks_frameobjects is bizarre:

--- lint.expected	2019-03-27 14:10:52.536094182 +0000
+++ /dev/fd/63	2019-03-27 14:10:52.536094182 +0000
@@ -11,3 +11,4 @@
 E: 34,38: FrameObject properties must use "self._frame", not "get_frame()" (stbt-frame-object-get-frame)
 E: 36,32: FrameObject properties must use "self._frame", not "get_frame()" (stbt-frame-object-get-frame)
 E: 40,15: FrameObject properties must not use "wait_for_match" (stbt-frame-object-property-single-frame)
+E: 40,15: Undefined variable 'wait_for_match' (undefined-variable)

If I remove the new checker, pylint doesn't report undefined-variable. The line in question is:

stb-tester/tests/test-stbt-lint.sh

Lines 237 to 239 in bdf74d6

	@property
	def another2(self):
	return stbt.wait_for_match("videotestsrc-redblue.png")

[drothlis]

Rebased onto main. The test failure is still happening with Ubuntu 22.04's version of pylint:

pylint 2.12.2
astroid 2.9.3
Python 3.10.4 (main, Apr  2 2022, 09:04:19) [GCC 11.2.0]

This is the line in the test-case:

stb-tester/tests/test-stbt-lint.sh

Lines 240 to 242 in a633b2f

	@property
	def another2(self):
	return stbt.wait_for_match("videotestsrc-redblue.png")

And this is the pylint output:

E: 40,15: FrameObject properties must not use "wait_for_match" (stbt-frame-object-property-single-frame)
E: 40,15: Undefined variable 'wait_for_match' (undefined-variable)

The first line is expected, the 2nd line isn't.

If I comment out this line, pylint doesn't show either message:

stb-tester/_stbt/pylint_plugin.py

Line 134 in a633b2f

self.add_message('E7010', node=node, args=node.func.as_string())

[drothlis]

Rebased onto main to get #762. The bug is still happening (pylint 2.14.3, astroid 2.11.6).