Eglot: declare eglot-lsp-context bound to non-nil

Otherwise, it'll be really hard to use it in the recommended fashion:

  (defun my/project-find-function (dir)
    (when-let ((match
                (and (bound-and-true-p eglot-lsp-context)
                     (locate-dominating-file dir "some-marker-file"))))
      `(transient . ,match)))

  (add-hook 'project-find-functions #'my/project-find-function)

because 'bound-and-true-p' will never return t even when the hook is called
from eglot--current-project.

Github-reference: https://github.com/joaotavora/eglot/discussions/1336
Github-reference: https://github.com/joaotavora/eglot/discussions/1337

* lisp/progmodes/eglot.el (eglot-lsp-context): Declare normally.
10 jobs for master in 93 minutes and 28 seconds (queued for 9 seconds)
Status Job ID Name Coverage
  Build Images
failed #78788
build-image-inotify

00:05:24

 
  Normal
skipped #78789
test-all-inotify
 
  Platform Images
failed #78790
build-image-eglot

01:33:00

failed #78792
build-image-gnustep

00:06:48

failed #78791
build-image-tree-sitter

01:33:23

 
  Platforms
skipped #78793
test-eglot
skipped #78795
test-gnustep
skipped #78794
test-tree-sitter
 
  Native Comp Images
failed #78796
build-native-comp-speed2

00:08:17

 
  Native Comp
skipped #78797
test-native-comp-speed2
 
Name Stage Failure
failed
build-image-tree-sitter Platform Images
f84c96d82328: Retrying in 1 second
1715d49645ec: Retrying in 5 seconds
context deadline exceeded (Client.Timeout exceeded while awaiting headers)
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-tree-sitter-9cb85e95: No such file or directory
ERROR: Job failed: exit code 1
failed
build-image-eglot Platform Images
context deadline exceeded (Client.Timeout exceeded while awaiting headers)
Running after_script
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-eglot-9cb85e95: No such file or directory
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
build-native-comp-speed2 Native Comp Images
$ docker login -u ${CI_REGISTRY_USER} -p ${CI_REGISTRY_PASSWORD} ${CI_REGISTRY}
WARNING! Using --password via the CLI is insecure. Use --password-stdin.
Error response from daemon: Get "https://emba.gnu.org:5050/v2/": Get "https://emba.gnu.org//jwt/auth?account=gitlab-ci-token&client_id=docker&offline_token=true&service=container_registry": net/http: request canceled (Client.Timeout exceeded while awaiting headers) (Client.Timeout exceeded while awaiting headers)
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-native-comp-speed2-9cb85e95: No such file or directory
ERROR: Job failed: exit code 1
failed
build-image-gnustep Platform Images
Error response from daemon: Get "https://emba.gnu.org:5050/v2/": Get "https://emba.gnu.org//jwt/auth?account=gitlab-ci-token&client_id=docker&offline_token=true&service=container_registry": net/http: request canceled (Client.Timeout exceeded while awaiting headers) (Client.Timeout exceeded while awaiting headers)
Running after_script
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-gnustep-9cb85e95: No such file or directory
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
build-image-inotify Build Images
 > [internal] load build context:
------
rpc error: code = Unavailable desc = transport is closing
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-inotify-9cb85e95: No such file or directory
ERROR: Job failed: exit code 1