Escape text content in cli

[tomchristie]

There's some cases where our console output can raise exceptions, because we're not currently escaping anything that might be interpreted by rich as a markup template tag.

Will has already done a little work on this here #1866 but I expect that it needs updating, and probably isn't complete.

Eg...

$ httpx https://cataas.com/cat 
HTTP/1.1 200 OK
Server: nginx/1.12.2
Date: Thu, 27 Jan 2022 11:19:17 GMT
Content-Type: image/jpeg
Content-Length: 40849
Connection: keep-alive
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: X-Requested-With, Content-Type, Accept, Origin, Authorization
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Cache-Control: public, max-age=30
ETag: 1643256053593

Traceback (most recent call last):
  File "venv/bin/httpx", line 11, in <module>
    load_entry_point('httpx', 'console_scripts', 'httpx')()
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/click/core.py", line 1128, in __call__
    return self.main(*args, **kwargs)
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/Users/tomchristie/GitHub/encode/httpx/httpx/_main.py", line 486, in main
    print_response(response)
  File "/Users/tomchristie/GitHub/encode/httpx/httpx/_main.py", line 176, in print_response
    console.print(response.text)
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/rich/console.py", line 1602, in print
    highlight=highlight,
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/rich/console.py", line 1460, in _collect_renderables
    renderable, emoji=emoji, markup=markup, highlighter=_highlighter
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/rich/console.py", line 1355, in render_str
    emoji_variant=self._emoji_variant,
  File "/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.7/site-packages/rich/markup.py", line 161, in render
    ) from None
rich.errors.MarkupError: closing tag '[/�$B����c}Nʌ��W�a�����}O��W��4Q;!�����0]' at position 3761 doesn't match any open tag

(Note that the above URL happens to return a random cat image, so you'll only sometimes see this error.)

[tomchristie]

Resolved in #1866 (I added one additional escape in there)