Allow entry_maker to return a flag to denote entries type

[dsych]

Description

What the tittle says.

This is useful when one is creating a live_grep like picker that makes a request to some url that returns a single json array with multiple entries. From the perspective of the oneshot job, the json is on a single line and has to be considered as a single entry, however this might not be what we actually want. Instead, we might want to parse the json and return multiple entries. For instance:
source line : "{someArray: [1, 2, 3]}" -> wanted entries : 1, 2, 3

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

I tested this with curl as a command that makes request to an http endpoint that returns a json. Also tested other pickers like live_grep, find_files, lsp pickers etc.

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list relevant details about your configuration

• Test A
• Test B

Configuration:

• Neovim version (nvim --version):

nvim --version
NVIM v0.9.0-dev-213+gcc5b7368d
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3
Compilation: /usr/bin/cc -DNVIM_TS_HAS_SET_MATCH_LIMIT -DNVIM_TS_HAS_SET_ALLOCATOR -O2 -g -Og -g -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wdouble-promotion -Wmissing-noreturn -Wmissing-format-attribute -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -DMIN_LOG_LEVEL=3 -I/home/dsych/.local/source/neovim/build/cmake.config -I/home/dsych/.local/source/neovim/src -I/home/dsych/.local/source/neovim/.deps/usr/include -I/usr/include -I/home/dsych/.local/source/neovim/build/src/nvim/auto -I/home/dsych/.local/source/neovim/build/include
Compiled by 

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/local/share/nvim"

Run :checkhealth for more info

• Operating system and version:
  Amazon Linux 2

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[Conni2461]

hmm i gotta think about this and if we can solve this with some configuration, so we are replacing the actual code that is running and dont have to do the consider multiple job in every iteration