lua plugin: add support for relative path scripts; moves inline script to switch

[randall]

To use inline scripts, prefix with --inline;
eg:
@plugin=tslua.so @pparam=--states=4 @pparam=--inline=print(123)

[shukitchan]

i think it looks good. Just a small comment.

[randall]

[approve ci autest]

[shukitchan]

I think you still make a good catch on line 204 on ts_lua_util.c that it is showing the error message with wrong parameter. So I recommend just to eliminate the "conf->script" parameter from the message altogether. thanks.

If not, I can do it on my own tonight as well.

Anyway, the rest all looks good. thanks.

[mlibbey]

Do we need a small doc update with this?

[randall]

@mlibbey What do you have in mind here?

[mlibbey]

The doc has this example
@pparam=/XXX/test_hdr.lua
Perhaps, "The path referencing a file with the lua script can be relative to the configuration directory or an absolute path."

Then some place in the config section, perhaps
The remap line can contain inline script via the inline keyword. For example
@pparam=--inline=print(123)
would run those lua statements directly.

[shukitchan]

I can add that in the weekend if Randall does not beat me to that.

[zwoop]

Cherry-picked to 8.1.x